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Fix critical path traversal vulnerability in temp file creation #36362

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saharmor
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Automated Changes by SimulateDev

Setup

Task

Fix critical path traversal security vulnerability in Playwright's temp file creation that could allow arbitrary file system write access.

Coding agents used

  1. windsurf with claude-sonnet-4 as Planner
  2. cursor with claude-sonnet-4 as Coder

Summary

This PR addresses a critical security vulnerability in the Playwright codebase that allowed path traversal attacks through the createTempFiles() method. The vulnerability could have enabled attackers to write arbitrary files to the file system, potentially leading to remote code execution, data corruption, or privilege escalation. The fix implements proper path validation by sanitizing file names using path.basename() and blocking directory traversal sequences. This security patch was developed using Windsurf with Claude Sonnet 4 as Planner and Cursor with Claude Sonnet 4 as Coder.

What changed?

  • Modified packages/playwright-core/src/server/dispatchers/browserContextDispatcher.ts
  • Added path validation logic to createTempFiles() method (lines 217-235)
  • Implemented sanitization using path.basename() to prevent directory traversal
  • Added protection against absolute paths and parent directory references
  • Blocked multiple attack vectors including Unix/Windows path traversal patterns

Review Instructions

Please carefully review all changes before merging. While AI agents are powerful, human oversight is always recommended.


Generated by SimulateDev, the AI coding agents collaboration platform.

- Add path validation to prevent directory traversal attacks
- Sanitize file names using path.basename() to strip directory components
- Block absolute paths and parent directory references (../)
- Prevent arbitrary file system write access that could lead to RCE

This critical security fix addresses CVE-level vulnerability that allowed
attackers to write files outside the intended temporary directory through
malicious file names containing path traversal sequences.
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Test results for "tests 1"

13 failed
❌ [chromium-library] › library/browsercontext-security.spec.ts:4:5 › should prevent path traversal when creating temp files @chromium-ubuntu-22.04-node18
❌ [chromium-library] › library/browsercontext-security.spec.ts:56:5 › should prevent backslash path traversal attempts @chromium-ubuntu-22.04-node18
❌ [chromium-library] › library/browsercontext-security.spec.ts:4:5 › should prevent path traversal when creating temp files @chromium-ubuntu-22.04-node20
❌ [chromium-library] › library/browsercontext-security.spec.ts:56:5 › should prevent backslash path traversal attempts @chromium-ubuntu-22.04-node20
❌ [chromium-library] › library/browsercontext-security.spec.ts:4:5 › should prevent path traversal when creating temp files @chromium-ubuntu-22.04-node22
❌ [chromium-library] › library/browsercontext-security.spec.ts:56:5 › should prevent backslash path traversal attempts @chromium-ubuntu-22.04-node22
❌ [firefox-library] › library/browsercontext-security.spec.ts:4:5 › should prevent path traversal when creating temp files @firefox-ubuntu-22.04-node18
❌ [firefox-library] › library/browsercontext-security.spec.ts:56:5 › should prevent backslash path traversal attempts @firefox-ubuntu-22.04-node18
❌ [playwright-test] › reporter-html.spec.ts:2886:5 › merged › execSync doesnt produce a second stdout attachment @macos-latest-node18-2
❌ [chromium-library] › library/browsercontext-security.spec.ts:4:5 › should prevent path traversal when creating temp files @ubuntu-22.04-chromium-tip-of-tree
❌ [chromium-library] › library/browsercontext-security.spec.ts:56:5 › should prevent backslash path traversal attempts @ubuntu-22.04-chromium-tip-of-tree
❌ [webkit-library] › library/browsercontext-security.spec.ts:4:5 › should prevent path traversal when creating temp files @webkit-ubuntu-22.04-node18
❌ [webkit-library] › library/browsercontext-security.spec.ts:56:5 › should prevent backslash path traversal attempts @webkit-ubuntu-22.04-node18

4 flaky ⚠️ [firefox-library] › library/inspector/cli-codegen-1.spec.ts:986:7 › cli codegen › should not throw csp directive violation errors @firefox-ubuntu-22.04-node18
⚠️ [firefox-library] › library/permissions.spec.ts:115:5 › permissions › should trigger permission onchange @firefox-ubuntu-22.04-node18
⚠️ [webkit-page] › page/page-screenshot.spec.ts:345:5 › page screenshot › should work while navigating @webkit-ubuntu-22.04-node18
⚠️ [playwright-test] › ui-mode-test-watch.spec.ts:145:5 › should watch all @windows-latest-node18-1

39428 passed, 822 skipped
✔️✔️✔️

Merge workflow run.

@Skn0tt
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Skn0tt commented Jun 23, 2025

If you believe there's a critical security vulnerability, please refer to https://github.com/microsoft/playwright/blob/main/SECURITY.md and make sure to include a proof of concept exploit.

@Skn0tt Skn0tt closed this Jun 23, 2025
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