fix(security): prevent command injection in findCommand via safe spawnSync by Ashutosh0x · Pull Request #27575 · google-gemini/gemini-cli

Ashutosh0x · 2026-05-30T04:50:12Z

Summary

Security fix: Replace shell-interpolated execSync calls with safe spawnSync/spawn to prevent command injection via shell metacharacters in two files:

packages/core/src/ide/ide-installer.ts — findCommand()
packages/core/src/utils/editor.ts — commandExists() and commandExistsAsync()

Fixes #27576

Details

Both files construct shell commands via string interpolation with execSync:

// ide-installer.ts (line 32, 41)
child_process.execSync(`where.exe ${command}`)
child_process.execSync(`command -v ${command}`)

// editor.ts (line 108-110, used at line 115 and 124)
function getCommandExistsCmd(cmd: string): string {
  return process.platform === 'win32'
    ? `where.exe ${cmd}`
    : `command -v ${cmd}`;
}
execSync(getCommandExistsCmd(cmd), { stdio: 'ignore' });

If the parameters contain shell metacharacters (;, |, `, $()), these are interpreted by the shell, allowing arbitrary command execution.

Fixes applied:

`ide-installer.ts`

Replace execSync with spawnSync using argument arrays (shell: false)
Add input validation regex (/^[a-zA-Z0-9.\-_/\\]+$/) as defense-in-depth
Use which instead of command -v (shell builtin incompatible with spawnSync)
Sanitize where.exe output with path.resolve() and null byte check

`editor.ts`

Replace execSync(getCommandExistsCmd(cmd)) with spawnSync('where.exe'/'which', [cmd])
Replace execAsync(getCommandExistsCmd(cmd)) with spawn('where.exe'/'which', [cmd])
Remove getCommandExistsCmd() helper (no longer needed)
Remove unused exec, execSync, promisify imports

Related Issues

Fixes #27576

How to Validate

Verify existing functionality: Run gemini-cli — editor detection and IDE installation should work as before
Verify injection is blocked: spawnSync/spawn with shell: false prevents shell metacharacter interpretation
Run unit tests: npm test in packages/core

Pre-Merge Checklist

…nSync Replace shell-interpolated execSync calls with spawnSync argument arrays to prevent command injection in the findCommand() utility function. Vulnerability: - execSync(`where.exe `) on Windows (line 32) - execSync(`command -v `) on Unix (line 41) Both construct shell commands via string interpolation, which allows command injection if the 'command' parameter contains shell metacharacters (e.g., semicolons, pipes, backticks). Fix: 1. Replace execSync with spawnSync using argument arrays (shell: false) to eliminate shell interpretation entirely 2. Add input validation regex to reject command names with metacharacters as defense-in-depth 3. Use 'which' instead of 'command -v' on Unix since spawnSync requires an executable (command is a shell builtin)

gemini-code-assist · 2026-05-30T04:50:21Z

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a potential command injection vulnerability in the findCommand utility. By moving away from shell-interpolated execution and implementing strict input validation, the change ensures that external commands are executed safely without risking arbitrary code execution. This aligns with ongoing security hardening efforts for the project.

Highlights

Security Hardening: Replaced vulnerable execSync calls with spawnSync using shell: false to prevent command injection via shell metacharacters.
Input Validation: Introduced a regex-based validation check to ensure command names only contain safe, alphanumeric characters and path separators.
Platform Compatibility: Updated Unix path resolution to use which instead of command -v to ensure compatibility with spawnSync.

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gemini-code-assist

Code Review

This pull request enhances security in packages/core/src/ide/ide-installer.ts by validating the command name against a safe regex pattern and replacing shell-interpolated execSync calls with safe spawnSync executions. The review feedback recommends further securing the output of where.exe by sanitizing and resolving the returned path to prevent potential path traversal or null byte injection vulnerabilities.

gemini-code-assist · 2026-05-30T04:51:59Z

+      if (result.status === 0 && result.stdout) {
+        const firstPath = result.stdout.trim().split(/\r?\n/)[0];
+        if (firstPath) {
+          return firstPath;
+        }
      }


The path returned by where.exe is extracted from command output, which is considered an untrusted source. To prevent potential path traversal (..) or null byte injection (\0) vulnerabilities, the path should be sanitized and resolved before being returned and executed, in accordance with our security rules.

Suggested change

if (result.status === 0 && result.stdout) {

const firstPath = result.stdout.trim().split(/\r?\n/)[0];

if (firstPath) {

return firstPath;

}

}

if (result.status === 0 && result.stdout) {

const firstPath = result.stdout.trim().split(/\r?\n/)[0];

if (firstPath && !firstPath.includes('\0') && !firstPath.includes('..')) {

return path.resolve(firstPath);

}

}

References

Sanitize file paths extracted from untrusted sources, such as command output, to prevent path traversal (..), null byte injection (\0), and other vulnerabilities.

Address Gemini Code Assist review: add path.resolve() and null byte check to sanitize the path returned by where.exe, preventing potential path traversal or null byte injection from untrusted command output.

…commandExistsAsync Same vulnerability as ide-installer.ts: execSync with shell-interpolated command names via getCommandExistsCmd(). Replaced with spawnSync/spawn using argument arrays (shell: false). - Removed getCommandExistsCmd() helper (no longer needed) - Removed unused exec, execSync, promisify imports - commandExists() now uses spawnSync('where.exe'/'which', [cmd]) - commandExistsAsync() now uses spawn('where.exe'/'which', [cmd])

Ashutosh0x requested a review from a team as a code owner May 30, 2026 04:50

gemini-code-assist Bot reviewed May 30, 2026

View reviewed changes

gemini-cli Bot added the status/need-issue Pull requests that need to have an associated issue. label May 30, 2026

Ashutosh0x added 2 commits May 30, 2026 12:51

fix: sanitize where.exe output path per review feedback

a62bf51

Address Gemini Code Assist review: add path.resolve() and null byte check to sanitize the path returned by where.exe, preventing potential path traversal or null byte injection from untrusted command output.

gemini-cli Bot added area/security Issues related to security priority/p2 Important but can be addressed in a future release. and removed status/need-issue Pull requests that need to have an associated issue. labels May 30, 2026

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fix(security): prevent command injection in findCommand via safe spawnSync#27575

fix(security): prevent command injection in findCommand via safe spawnSync#27575
Ashutosh0x wants to merge 3 commits into
google-gemini:mainfrom
Ashutosh0x:fix/command-injection-ide-installer

Ashutosh0x commented May 30, 2026 •

edited

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Ashutosh0x commented May 30, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Summary

Details

ide-installer.ts

editor.ts

Related Issues

How to Validate

Pre-Merge Checklist

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gemini-code-assist Bot commented May 30, 2026

Summary of Changes

Highlights

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Ashutosh0x commented May 30, 2026 •

edited

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`ide-installer.ts`

`editor.ts`