AIKIDO-2026-10871
symfony/html-sanitizer is vulnerable to Interpretation Conflict
61
Medium Risk
This Affects:
symfony/html-sanitizerTL;DR
allowLinkHosts() and allowMediaHosts() rely on URL parsing that differs from browser URL handling. Backslashes, unusual slash counts, and area element handling can make a URL pass server-side allowlists while navigating elsewhere in the browser. Pre-fix sanitized content can smuggle off-allowlist link or media targets. The fix rejects parser-differential URL forms and applies link policy to area elements.
Who does this affect?
You are affected if you are using a version that falls within the vulnerable range.
Background info
symfony/html-sanitizer is vulnerable to Interpretation Conflict in versions 6.1.0 - 6.4.39, 7.0.0 - 7.4.11 and 8.0.0 - 8.0.11.
How to fix this
Upgrade the symfony/html-sanitizer and/or symfony/symfony library to the patch version.
Links
GitHub Releases
github.com/symfony/html-sanitizer/releases/tag/v8.0.12github.com/symfony/symfony/releases/tag/v6.4.40github.com/symfony/symfony/releases/tag/v7.4.12github.com/symfony/symfony/releases/tag/v8.0.12
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