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

PostCSS: XSS via Unescaped in CSS Stringify Output Summary PostCSS v8.5.5 latest does not escape sequences when stringifying CSS ASTs. When user-submitted CSS is parsed and re-stringified for embedding in HTML tags, in CSS values breaks out of the style context, enabling XSS. Proof of Concept...

CVE-2026-41305 PostCSS has XSS via Unescaped </style> in its CSS Stringify Output

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 sequences when stringifying CSS ASTs. When user-submitted CSS is parsed and re-stringified for embedding in HTML tags, in CSS...