GHSA-QX2V-QP2M-JG93 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...

Cross-site Scripting (XSS)

Overview org.webjars.npm:postcss is a PostCSS is a tool for transforming styles with JS plugins. Affected versions of this package are vulnerable to Cross-site Scripting XSS in CSS Stringify Output. An attacker can execute arbitrary JavaScript code in the context of the affected web page by...

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...