fix: SEC-4653 prevent ReDoS vulnerability in HTML payload unwrapping regex #686
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Fixed a polynomial Regular Expression Denial of Service (ReDoS) vulnerability in the HTML payload unwrapping function. The base64 capture group in the regex pattern was changed from greedy (`+`) to non-greedy (`+?`) to prevent exponential backtracking when processing malicious input. **Security Impact:** - Prevents potential DoS attacks through crafted HTML input that could cause excessive CPU usage - Maintains the same functional behavior for legitimate base64 payload extraction **Technical Details:** - Modified regex pattern in `lib/tdf3/src/utils/unwrap.ts` line 6 - Changed `([a-zA-Z0-9+/=]+)` to `([a-zA-Z0-9+/=]+?)` to use non-greedy matching - This eliminates catastrophic backtracking scenarios while preserving correct base64 extraction
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Summary of Changes
Hello @jentfoo, 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 critical security vulnerability by preventing potential Regular Expression Denial of Service (ReDoS) attacks. It ensures the application remains robust against maliciously crafted HTML inputs while preserving its intended functionality for legitimate data extraction.
Highlights
- Security Fix (ReDoS): Implemented a fix to prevent a Regular Expression Denial of Service (ReDoS) vulnerability in the HTML payload unwrapping function, safeguarding against potential DoS attacks caused by maliciously crafted HTML input.
- Regex Optimization: Modified the regex pattern used for HTML payload extraction by changing the base64 capture group's quantifier from greedy (
+) to non-greedy (+?). This change specifically addresses and eliminates catastrophic backtracking scenarios without altering the functional behavior for legitimate inputs.
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Code Review
This pull request addresses a potential polynomial ReDoS vulnerability in the HTML unwrapping logic by changing a greedy quantifier to a non-greedy one in the payload extraction regex. The change is correct and improves the robustness of the parser against malicious inputs. I've added one suggestion to further improve the regex by adding support for URL-safe base64 characters, which would prevent potential issues with valid TDFs that use this encoding.
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
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Fixed a polynomial Regular Expression Denial of Service (ReDoS) vulnerability in the HTML payload unwrapping function. The base64 capture group in the regex pattern was changed from greedy (
+) to non-greedy (+?) to prevent exponential backtracking when processing malicious input.Security Impact:
Technical Details:
lib/tdf3/src/utils/unwrap.tsline 6([a-zA-Z0-9+/=]+)to([a-zA-Z0-9+/=]+?)to use non-greedy matching