CVE-2026-41305 — PostCSS has XSS via Unescaped in its CSS Stringify Output

Affected: postcss

PostCSS takes a CSS file and provides an API to analyze and modify its rules by transforming the rules into an Abstract Syntax Tree. Versions prior to 8.5.10 do not escape `</style>` sequences when stringifying CSS ASTs. When user-submitted CSS is parsed and re-stringified for embedding in HTML `<style>` tags, `</style>` in CSS values breaks out of the style context, enabling XSS. Version 8.5.10 fixes the issue.

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CVE-2026-41305 — PostCSS has XSS via Unescaped in its CSS Stringify Output