PostCSS has XSS via Unescaped </style> in its CSS Stringify Output
CVE-2026-41305 is fixed in node-postcss on 1 platform by DEBIAN-CVE-2026-41305 (version 8.5.12+~cs9.3.32-1), released May 15, 2026. It is not reported as exploited. Patch Radar priority: Routine.
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.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| node-postcss · Debian 14 | 8.5.12+~cs9.3.32-1 | DEBIAN-CVE-2026-41305 | May 15, 2026 |
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