Security context

What an agent needs to avoid regressing past fixes and find the next vuln in this repo.

mozilla/bleach

              main @ f0355a7
            

Fixes

CVEs

CRITICAL

Peak severity

20.0%

Coverage

Highlights

Cross-Site Scripting (XSS): 4 prior fixes. Scrutinize any change in this area.

bleach/sanitizer.py: most-fixed (4 issues). Treat as high-risk during review.

4 high-severity fixes in this history; regressions here are high-impact.

Recurring patterns

The bug types that recur here, drawn from past fixes, not open vulnerabilities.

Cross-Site Scripting (XSS): Mutation-based XSS (mXSS) represents a high-severity threat when handling structural tags (like SVG, MathML, or RCDATA elements) and comments when 'strip_comments' is disabled, allowing bypasses that execute when parsed by browsers.

Reflected XSS: Sanitizer bypasses can occur when validating URI schemes if non-ASCII characters or malformed layouts are not properly stripped prior to scheme evaluation, allowing malicious payloads like 'javascript:' execution.

Cross-Site Scripting (XSS): Incomplete parsing or handling of raw tokens (such as AtRule and ParseError) in CSS declaration lists can lead to stylesheet-based bypasses, necessitating structured parsing via tinycss2.