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Sep 14, 2025
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Added 10 reentrancy vulnerability type smart contracts #94

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15 changes: 15 additions & 0 deletions audit_engine/smart_contracts/reentrancy/40499.sol
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contract Wallet {


mapping (address => uint) m_txs;

function confirm(address _h, uint value, byte data) returns (bool) {
if (m_txs[_h] != 0) {
_h.call.value(value)(data);
m_txs[_h] -= value;
return true;
}
}
Comment on lines +7 to +13
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⚠️ Potential issue

Multiple issues: reentrancy, unchecked call result, and underflow.

  • External call before decrement (reentrancy).
  • Not checking call success.
  • m_txs[_h] can underflow if value > balance.
  • byte is a single byte; likely meant bytes.
-    function confirm(address _h, uint value, byte data) returns (bool) {
-        if (m_txs[_h] != 0) {
-            _h.call.value(value)(data);
-            m_txs[_h] -= value;
-            return true;
-        }
-    }
+    function confirm(address _h, uint value, bytes data) returns (bool) {
+        uint bal = m_txs[_h];
+        if (bal == 0 || value == 0) { return false; }
+        require(bal >= value);
+        m_txs[_h] = bal - value; // effects first
+        require(_h.call.value(value)(data)); // interaction after
+        return true;
+    }
📝 Committable suggestion

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Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
function confirm(address _h, uint value, byte data) returns (bool) {
if (m_txs[_h] != 0) {
_h.call.value(value)(data);
m_txs[_h] -= value;
return true;
}
}
function confirm(address _h, uint value, bytes data) returns (bool) {
uint bal = m_txs[_h];
if (bal == 0 || value == 0) { return false; }
require(bal >= value);
m_txs[_h] = bal - value; // effects first
require(_h.call.value(value)(data)); // interaction after
return true;
}
🤖 Prompt for AI Agents 
In audit_engine/smart_contracts/reentrancy/40499.sol around lines 7-13: the
function performs an external call before updating state, doesn't check the call
result, allows underflow by not ensuring value <= m_txs[_h], and uses byte
instead of bytes; fix by first require(value <= m_txs[_h]) to prevent underflow,
subtract m_txs[_h] -= value before any external call (or use the
Checks-Effects-Interactions pattern), change the parameter type from byte to
bytes (or bytes calldata for external functions), perform the external call
using (bool success, ) = _h.call{value: value}(data) and require(success) (or
handle failure), and mark appropriate visibility and return behaviour so the
function explicitly returns a boolean.

}

10 changes: 10 additions & 0 deletions audit_engine/smart_contracts/reentrancy/40732.sol
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contract Bank{

mapping (address => uint256) public balances;

function withdraw() {
require(msg.sender.call.value(balances[msg.sender])());
balances[msg.sender] = 0;
}
}
13 changes: 13 additions & 0 deletions audit_engine/smart_contracts/reentrancy/40735.sol
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contract dumbDAO {
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🛠️ Refactor suggestion

Add SPDX and explicit pragma.

+// SPDX-License-Identifier: UNLICENSED
+pragma solidity 0.4.26;
 
 contract dumbDAO {
📝 Committable suggestion

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Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
contract dumbDAO {
// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.4.26;
contract dumbDAO {
🤖 Prompt for AI Agents 
In audit_engine/smart_contracts/reentrancy/40735.sol around lines 1 to 2, the
file is missing an SPDX license identifier and an explicit pragma solidity
directive; add a SPDX-License-Identifier comment at the top (e.g., a permissive
or project-consistent identifier) and add a pragma solidity statement specifying
the compiler version range (e.g., a caret version like ^0.8.0 or the exact
minimum required by the code) as the first non-comment lines so the compiler and
license scanners can correctly process the contract.


mapping (address => uint) public balances;

function withdraw(address _recipient) returns (bool) {

if (_recipient.call.value(balances[msg.sender])()) {
balances[msg.sender] = 0;
return true;
}
}
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🛠️ Refactor suggestion

⚠️ Potential issue

Reentrancy + missing visibility + ambiguous return path.

  • External call to arbitrary _recipient before zeroing balance enables reentrancy.
  • Visibility not specified (breaks ≥0.5).
  • On failure path, function implicitly returns false; be explicit.
-    function withdraw(address _recipient) returns (bool) {
-
-        if (_recipient.call.value(balances[msg.sender])()) {
-            balances[msg.sender] = 0;
-            return true;
-        }
-    }
+    function withdraw(address _recipient) public returns (bool) {
+        uint amount = balances[msg.sender];
+        require(amount > 0);
+        balances[msg.sender] = 0; // effects
+        if (!_recipient.call.value(amount)()) {
+            balances[msg.sender] = amount; // restore on failure
+            return false;
+        }
+        return true;
+    }

If intentionally vulnerable, add a clear header comment stating so instead of fixing logic.

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Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
function withdraw(address _recipient) returns (bool) {
if (_recipient.call.value(balances[msg.sender])()) {
balances[msg.sender] = 0;
return true;
}
}
function withdraw(address _recipient) public returns (bool) {
uint amount = balances[msg.sender];
require(amount > 0);
balances[msg.sender] = 0; // effects
if (!_recipient.call.value(amount)()) {
balances[msg.sender] = amount; // restore on failure
return false;
}
return true;
}
🤖 Prompt for AI Agents 
In audit_engine/smart_contracts/reentrancy/40735.sol around lines 6–12, the
withdraw function makes an external call before clearing the caller's balance
(reentrancy risk), lacks visibility, and has an ambiguous return path; fix by
declaring visibility (e.g., public), require the recipient be payable (address
payable _recipient), follow checks-effects-interactions: read
balances[msg.sender] into a local amount, set balances[msg.sender] = 0 before
the external call, perform the external transfer using a safe pattern (or use
call and capture success), on call failure restore the balance and return false
explicitly, and on success return true.

}
14 changes: 14 additions & 0 deletions audit_engine/smart_contracts/reentrancy/40736.sol
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contract EtherStore {
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🛠️ Refactor suggestion

Add SPDX and pin pragma.

+// SPDX-License-Identifier: UNLICENSED
+pragma solidity 0.4.26;
 
 contract EtherStore {
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Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
contract EtherStore {
// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.4.26;
contract EtherStore {
🤖 Prompt for AI Agents 
In audit_engine/smart_contracts/reentrancy/40736.sol around lines 1 to 2, the
file is missing an SPDX license identifier and a pinned pragma version; add a
SPDX header (e.g., // SPDX-License-Identifier: MIT) as the first line and add a
specific, pinned pragma solidity statement (e.g., pragma solidity 0.8.19;) on
the next line so the compiler version is explicit and licensing is declared.


uint256 public withdrawalLimit = 1 ether;
mapping(address => uint256) public balances;

function withdrawFunds (uint256 _weiToWithdraw) public {
require(balances[msg.sender] >= _weiToWithdraw);
require(_weiToWithdraw <= withdrawalLimit);
require(msg.sender.call.value(_weiToWithdraw)());
balances[msg.sender] -= _weiToWithdraw;
}
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🛠️ Refactor suggestion

⚠️ Potential issue

Reentrancy in withdrawFunds (CEI violated).

Calls msg.sender before reducing balance. Fix by moving effects before interactions; optionally add a reentrancy guard.

-    function withdrawFunds (uint256 _weiToWithdraw) public {
-        require(balances[msg.sender] >= _weiToWithdraw);
-        require(_weiToWithdraw <= withdrawalLimit);
-        require(msg.sender.call.value(_weiToWithdraw)());
-        balances[msg.sender] -= _weiToWithdraw;
-    }
+    function withdrawFunds (uint256 _weiToWithdraw) public {
+        require(balances[msg.sender] >= _weiToWithdraw);
+        require(_weiToWithdraw <= withdrawalLimit);
+        balances[msg.sender] -= _weiToWithdraw; // effects
+        require(msg.sender.call.value(_weiToWithdraw)()); // interaction
+    }

Optional: add a simple nonReentrant modifier.

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Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
function withdrawFunds (uint256 _weiToWithdraw) public {
require(balances[msg.sender] >= _weiToWithdraw);
require(_weiToWithdraw <= withdrawalLimit);
require(msg.sender.call.value(_weiToWithdraw)());
balances[msg.sender] -= _weiToWithdraw;
}
function withdrawFunds (uint256 _weiToWithdraw) public {
require(balances[msg.sender] >= _weiToWithdraw);
require(_weiToWithdraw <= withdrawalLimit);
balances[msg.sender] -= _weiToWithdraw; // effects
require(msg.sender.call.value(_weiToWithdraw)()); // interaction
}
🤖 Prompt for AI Agents 
In audit_engine/smart_contracts/reentrancy/40736.sol around lines 7–12,
withdrawFunds currently violates the checks-effects-interactions pattern by
calling msg.sender.call.value(...)() before reducing the caller's balance; move
the state change so balances[msg.sender] is decremented (or set to zero) before
any external call, then perform the external transfer and check its return;
additionally, replace raw call usage with a safer pattern (check returned
success explicitly) and/or add a simple nonReentrant modifier (mutex bool guard)
on withdrawFunds to prevent reentrant entry.

}

10 changes: 10 additions & 0 deletions audit_engine/smart_contracts/reentrancy/40742.sol
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contract SendBalance {

mapping (address => uint) userBalances ;

function withdrawBalance() {
if (!(msg.sender.call.value(userBalances[msg.sender])())) { throw ; }
userBalances[msg.sender] = 0;
}
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⚠️ Potential issue

Legacy throw + reentrancy window; state updated after external call.

Replace throw with require/revert; move zeroing before the call (CEI). Also gate zero-withdrawals.

-    function withdrawBalance() {
-        if (!(msg.sender.call.value(userBalances[msg.sender])())) { throw ; }
-        userBalances[msg.sender] = 0;
-    }
+    function withdrawBalance() {
+        uint amount = userBalances[msg.sender];
+        require(amount > 0);
+        userBalances[msg.sender] = 0; // effects
+        require(msg.sender.call.value(amount)()); // interaction
+    }
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Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
function withdrawBalance() {
if (!(msg.sender.call.value(userBalances[msg.sender])())) { throw ; }
userBalances[msg.sender] = 0;
}
function withdrawBalance() {
uint amount = userBalances[msg.sender];
require(amount > 0);
userBalances[msg.sender] = 0; // effects
require(msg.sender.call.value(amount)()); // interaction
}
🤖 Prompt for AI Agents 
In audit_engine/smart_contracts/reentrancy/40742.sol around lines 6–9, the
function uses legacy throw, updates user state after an external call
(reentrancy risk), and allows zero-value withdrawals; fix by first reading the
withdraw amount into a local variable and require(amount > 0), then set
userBalances[msg.sender] = 0 before any external interaction (CEI), and finally
perform the ether transfer while replacing legacy throw with require/revert that
checks the call/transfer success; prefer the modern safe pattern ((bool ok, ) =
msg.sender.call{value: amount}("")) and require(ok) or use transfer/send with
proper handling depending on the Solidity version.

}
12 changes: 12 additions & 0 deletions audit_engine/smart_contracts/reentrancy/40745.sol
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contract SimpleDAO {
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🛠️ Refactor suggestion

Add SPDX and pragma for deterministic builds.

+// SPDX-License-Identifier: UNLICENSED
+pragma solidity 0.4.26;
 
 contract SimpleDAO {
📝 Committable suggestion

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Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
contract SimpleDAO {
// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.4.26;
contract SimpleDAO {
🤖 Prompt for AI Agents 
In audit_engine/smart_contracts/reentrancy/40745.sol around lines 1-2, the file
is missing an SPDX license identifier and a pragma solidity directive which are
required for deterministic builds; add a single SPDX license comment (e.g.,
"SPDX-License-Identifier: MIT") as the first line and a fixed pragma solidity
version (e.g., "pragma solidity 0.8.19;") immediately after it, placing both at
the top of the file before the contract declaration.


mapping (address => uint) public credit;

function withdraw(uint amount) {
if (credit[msg.sender] >= amount) {
msg.sender.call.value(amount)();
credit[msg.sender] -= amount;
}
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⚠️ Potential issue

Unchecked low-level call + CEI violated → reentrancy.

Return value is ignored and balance is reduced after the call.

-    function withdraw(uint amount) {
-        if (credit[msg.sender] >= amount) {
-          msg.sender.call.value(amount)();
-          credit[msg.sender] -= amount;
-        }
-    }
+    function withdraw(uint amount) public {
+        require(credit[msg.sender] >= amount);
+        credit[msg.sender] -= amount; // effects
+        require(msg.sender.call.value(amount)()); // interaction
+    }

If kept vulnerable on purpose, add an explicit “INTENTIONALLY VULNERABLE (reentrancy)” banner.

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Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
function withdraw(uint amount) {
if (credit[msg.sender] >= amount) {
msg.sender.call.value(amount)();
credit[msg.sender] -= amount;
}
function withdraw(uint amount) public {
require(credit[msg.sender] >= amount);
credit[msg.sender] -= amount; // effects
require(msg.sender.call.value(amount)()); // interaction
}
🤖 Prompt for AI Agents 
In audit_engine/smart_contracts/reentrancy/40745.sol around lines 6 to 10, the
withdraw function performs an unchecked low-level external call before updating
the caller's balance and ignores the call return value, enabling reentrancy; fix
it by following CEI: decrement credit[msg.sender] before making the external
call, replace msg.sender.call.value(amount)() with a safe pattern (preferably
use transfer() or check the returned bool from call and revert on failure), or
wrap the function with a reentrancy guard; if this contract is intentionally
vulnerable, add an explicit "INTENTIONALLY VULNERABLE (reentrancy)" banner at
the top of the file.

}
}
12 changes: 12 additions & 0 deletions audit_engine/smart_contracts/reentrancy/40746.sol
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contract Victim {
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🛠️ Refactor suggestion

Missing SPDX and pragma; code targets 0.4.x features.

+// SPDX-License-Identifier: UNLICENSED
+pragma solidity 0.4.26;
 
 contract Victim {
📝 Committable suggestion

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Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
contract Victim {
// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.4.26;
contract Victim {
🤖 Prompt for AI Agents 
In audit_engine/smart_contracts/reentrancy/40746.sol around lines 1 to 2, the
file is missing an SPDX license identifier and a Solidity pragma; add a
top-of-file SPDX comment (e.g. // SPDX-License-Identifier: MIT) on line 1 and
immediately below it add a pragma solidity statement matching the 0.4.x series
used by the contract (e.g. pragma solidity ^0.4.24; or the exact 0.4.x compiler
version required by the code).


mapping(address => uint) public balances;

function withdraw(uint _amount) public {
if(balances[msg.sender] >= _amount) {
if(!msg.sender.call.value(_amount)()) { throw; }
balances[msg.sender] -= _amount;
}
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⚠️ Potential issue

Reentrancy and deprecated throw.

External call precedes state update; throw is deprecated (use require/revert).

-    function withdraw(uint _amount) public {
-        if(balances[msg.sender] >= _amount) {
-            if(!msg.sender.call.value(_amount)()) { throw; }
-            balances[msg.sender] -= _amount;
-        }
-    }
+    function withdraw(uint _amount) public {
+        require(balances[msg.sender] >= _amount);
+        balances[msg.sender] -= _amount; // effects
+        require(msg.sender.call.value(_amount)()); // interaction
+    }

If this must stay vulnerable, annotate with a loud “DO NOT DEPLOY – reentrancy example” comment.

📝 Committable suggestion

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Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
function withdraw(uint _amount) public {
if(balances[msg.sender] >= _amount) {
if(!msg.sender.call.value(_amount)()) { throw; }
balances[msg.sender] -= _amount;
}
function withdraw(uint _amount) public {
require(balances[msg.sender] >= _amount);
balances[msg.sender] -= _amount; // effects
require(msg.sender.call.value(_amount)()); // interaction
}
🤖 Prompt for AI Agents 
In audit_engine/smart_contracts/reentrancy/40746.sol around lines 6 to 10, the
function performs an external call before updating state and uses the deprecated
throw; change to follow Checks-Effects-Interactions: use require to validate the
balance, subtract the _amount from balances[msg.sender] before making the
external transfer, and replace throw with a require that checks the call result
(or prefer a safe transfer pattern like transfer for fixed gas or
pull-payments); if the insecure order is intentional for demonstration, add a
prominent "DO NOT DEPLOY – reentrancy example" comment above the function.

}
}
15 changes: 15 additions & 0 deletions audit_engine/smart_contracts/reentrancy/40747.sol
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contract PIGGY_BANK {
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💡 Verification agent

🧩 Analysis chain

Pin compiler and add SPDX; code uses pre-0.6 syntax.

Without an explicit pragma these may compile against incompatible solc versions.

+// SPDX-License-Identifier: UNLICENSED
+pragma solidity 0.4.26;
 
 contract PIGGY_BANK {

Run to confirm pragma consistency across the repo:

🏁 Script executed:

#!/bin/bash
rg -n --glob '**/*.sol' 'pragma solidity'

Length of output: 0

🏁 Script executed:

#!/bin/bash
set -euo pipefail
echo "PWD: $(pwd)"
echo "Checking for the specific reviewed file:"
if [ -f "audit_engine/smart_contracts/reentrancy/40747.sol" ]; then
  echo "FOUND: audit_engine/smart_contracts/reentrancy/40747.sol"
  sed -n '1,120p' audit_engine/smart_contracts/reentrancy/40747.sol || true
else
  echo "Not found: audit_engine/smart_contracts/reentrancy/40747.sol"
fi

echo
echo "Searching repository for .sol files..."
mapfile -t sols < <(find . -type f -name '*.sol' -print)
if [ ${#sols[@]} -eq 0 ]; then
  echo "No .sol files found in repo."
  exit 0
fi

echo "Found ${#sols[@]} .sol files. Printing first 40 lines of each (filename header included):"
for f in "${sols[@]}"; do
  echo "---- FILE: $f ----"
  sed -n '1,40p' "$f" || true
done

echo
echo "Searching those files for 'pragma solidity' and 'SPDX-License-Identifier':"
for f in "${sols[@]}"; do
  if grep -nE '^\s*pragma\s+solidity|SPDX-License-Identifier' "$f" >/dev/null 2>&1; then
    echo "$f matches:"
    grep -nE '^\s*pragma\s+solidity|SPDX-License-Identifier' "$f" || true
  fi
done

Length of output: 591

Add SPDX header and pin Solidity pragma; fix reentrancy in Collect.

audit_engine/smart_contracts/reentrancy/40747.sol is missing an SPDX header and pragma (it uses pre-0.5 syntax). Add a pinned pragma (e.g. 0.4.26) and SPDX. Also fix the reentrancy: Collect calls msg.sender.call.value(_am)() before updating Accounts[msg.sender] — move the state update before the external call or switch to a withdraw/pull pattern and/or add a reentrancy guard.

+// SPDX-License-Identifier: UNLICENSED
+pragma solidity 0.4.26;
 
 contract PIGGY_BANK {

Committable suggestion skipped: line range outside the PR's diff.

🤖 Prompt for AI Agents 
In audit_engine/smart_contracts/reentrancy/40747.sol around lines 1-2, add an
SPDX license header and pin the Solidity pragma to a specific compiler version
(e.g. pragma solidity 0.4.26;) at the top of the file, and fix the reentrancy in
the Collect function by updating Accounts[msg.sender] (set to zero or subtract
_am) before making any external call to msg.sender (or refactor to a
pull/withdraw pattern where users call withdraw to receive funds), and/or add a
simple reentrancy guard (bool locked) to prevent reentrant entries; ensure any
external call uses a safe method (prefer transfer in 0.4.26 or
check-effects-interactions) after state changes.


mapping (address => uint) public Accounts;
uint public MinSum = 1 ether;
uint putBlock;

function Collect(uint _am) public payable {
if(Accounts[msg.sender] >= MinSum && _am <= Accounts[msg.sender]) {
if(msg.sender.call.value(_am)()) {
Accounts[msg.sender] -= _am;
}
}
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⚠️ Potential issue

Reentrancy via external call before state update (CEI violated).

External call forwards all gas and occurs before debiting balance; attacker can re-enter Collect and drain. If this is not intentionally vulnerable, apply CEI and check the call result.

Apply this diff:

-    function Collect(uint _am) public payable {
-        if(Accounts[msg.sender] >= MinSum && _am <= Accounts[msg.sender]) {
-            if(msg.sender.call.value(_am)()) {
-                Accounts[msg.sender] -= _am;
-            }
-        }
-    }
+    function Collect(uint _am) public payable {
+        require(Accounts[msg.sender] >= MinSum && _am <= Accounts[msg.sender]);
+        Accounts[msg.sender] -= _am; // effects
+        require(msg.sender.call.value(_am)()); // interaction
+    }

If this contract is intentionally vulnerable, add a prominent “DO NOT DEPLOY – intentionally vulnerable (reentrancy)” header.

📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
function Collect(uint _am) public payable {
if(Accounts[msg.sender] >= MinSum && _am <= Accounts[msg.sender]) {
if(msg.sender.call.value(_am)()) {
Accounts[msg.sender] -= _am;
}
}
function Collect(uint _am) public payable {
require(Accounts[msg.sender] >= MinSum && _am <= Accounts[msg.sender]);
Accounts[msg.sender] -= _am; // effects
require(msg.sender.call.value(_am)()); // interaction
}
🤖 Prompt for AI Agents 
In audit_engine/smart_contracts/reentrancy/40747.sol around lines 8 to 13, the
function Collect performs an external call (msg.sender.call.value(_am)()) before
updating Accounts[msg.sender], violating the Checks-Effects-Interactions pattern
and allowing reentrancy; to fix, validate _am against balance first, then
decrement Accounts[msg.sender] (effect) before making the external transfer
(interaction), use a safer transfer pattern (e.g., send/transfer or call with
proper checks and limited gas) and require the call to succeed (revert on
failure); alternatively, if the contract is intentionally vulnerable add a
prominent “DO NOT DEPLOY – intentionally vulnerable (reentrancy)” header at the
top of the file.

}
}
10 changes: 10 additions & 0 deletions audit_engine/smart_contracts/reentrancy/40748.sol
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Original file line number Diff line number Diff line change
@@ -0,0 +1,10 @@

contract BancorBuyer {

mapping(address => uint256) public balances;

function buyOne(address _exchange, uint256 _value, bytes _data) payable public {
require(_exchange.call.value(_value)(_data));
balances[msg.sender] = balances[msg.sender] - _value;
}
Comment on lines +6 to +9
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⚠️ Potential issue

Unchecked subtraction can underflow; also CEI violation enables reentrancy.

If balances[msg.sender] < _value (pre-0.8), Line 8 underflows. Deduct before the call with a bound check; then perform the external call.

-    function buyOne(address _exchange, uint256 _value, bytes _data) payable public {
-        require(_exchange.call.value(_value)(_data));
-        balances[msg.sender] = balances[msg.sender] - _value;
-    }
+    function buyOne(address _exchange, uint256 _value, bytes _data) payable public {
+        require(balances[msg.sender] >= _value);
+        balances[msg.sender] -= _value; // effects
+        require(_exchange.call.value(_value)(_data)); // interaction
+    }
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
function buyOne(address _exchange, uint256 _value, bytes _data) payable public {
require(_exchange.call.value(_value)(_data));
balances[msg.sender] = balances[msg.sender] - _value;
}
function buyOne(address _exchange, uint256 _value, bytes _data) payable public {
require(balances[msg.sender] >= _value);
balances[msg.sender] -= _value; // effects
require(_exchange.call.value(_value)(_data)); // interaction
}
🤖 Prompt for AI Agents 
In audit_engine/smart_contracts/reentrancy/40748.sol around lines 6 to 9, the
function performs an external call before updating state and subtracts without
checking the balance, which can underflow and enables reentrancy; fix by first
requiring balances[msg.sender] >= _value, decrementing balances[msg.sender] by
_value (the “checks-effects” step), then performing the external call, and
consider using a safe call pattern (e.g. limit gas/handle the returned success)
to avoid reentrancy risks.

}
10 changes: 10 additions & 0 deletions audit_engine/smart_contracts/reentrancy/40749.sol
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Original file line number Diff line number Diff line change
@@ -0,0 +1,10 @@

contract Bank{
Comment on lines +1 to +2
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🛠️ Refactor suggestion

Missing SPDX and pragma; legacy syntax requires 0.4.x.

Without a pragma these files may compile against 0.8.x and fail. Pin a 0.4.x compiler (throw/call.value syntax compatible) and add license.

+pragma solidity 0.4.24;
+// SPDX-License-Identifier: UNLICENSED
+
 contract Bank{
📝 Committable suggestion

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Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
contract Bank{
pragma solidity 0.4.24;
// SPDX-License-Identifier: UNLICENSED
contract Bank{
🤖 Prompt for AI Agents 
In audit_engine/smart_contracts/reentrancy/40749.sol around lines 1-2, the file
lacks an SPDX license identifier and a pragma solidity statement which risks
compiling under newer 0.8.x compilers; add a top-of-file SPDX comment (e.g. //
SPDX-License-Identifier: MIT) and pin the compiler to a 0.4.x version compatible
with legacy throw/call.value syntax (e.g. pragma solidity ^0.4.24;) so the
contract compiles with the intended 0.4.x toolchain.


mapping (address => uint256) public balances;

function withdraw(){
require(msg.sender.call.value(balances[msg.sender])());
balances[msg.sender] = 0;
}
Comment on lines +6 to +9
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⚠️ Potential issue

Reentrancy: external call before zeroing balance (CEI violation).

Attacker can reenter via fallback before Line 8 and drain funds. Zero-out balance before the call and gate zero withdrawals.

Apply:

-    function withdraw(){
-        require(msg.sender.call.value(balances[msg.sender])());
-        balances[msg.sender] = 0;
-    }
+    function withdraw() {
+        uint256 amount = balances[msg.sender];
+        require(amount > 0);
+        balances[msg.sender] = 0; // effects first
+        require(msg.sender.call.value(amount)()); // interaction after
+    }
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
function withdraw(){
require(msg.sender.call.value(balances[msg.sender])());
balances[msg.sender] = 0;
}
function withdraw() {
uint256 amount = balances[msg.sender];
require(amount > 0);
balances[msg.sender] = 0; // effects first
require(msg.sender.call.value(amount)()); // interaction after
}
🤖 Prompt for AI Agents 
In audit_engine/smart_contracts/reentrancy/40749.sol around lines 6 to 9, the
withdraw function performs an external call before zeroing the sender's balance,
allowing reentrancy; change the logic to follow Checks-Effects-Interactions:
first require that balances[msg.sender] > 0, cache the amount to a local
variable, set balances[msg.sender] = 0, then perform the external transfer and
check its return value; alternatively use a reentrancy guard or the pull pattern
(allow owner to withdraw via a withdrawal queue) and avoid using raw
call.value() without proper checks.

}