Skip to content
CVE PROGRAM SOURCE RECORD6.1 Medium

CVE-2026-41305

PostCSS has XSS via Unescaped </style> in its CSS Stringify Output

Description

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

postcss postcss

  • < 8.5.10affected

References