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.
History

Mon, 27 Apr 2026 19:30:00 +0000

Type Values Removed Values Added
First Time appeared Postcss
Postcss postcss
Vendors & Products Postcss
Postcss postcss

Sun, 26 Apr 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Moderate


Fri, 24 Apr 2026 17:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 24 Apr 2026 02:45:00 +0000

Type Values Removed Values Added
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.
Title PostCSS has XSS via Unescaped </style> in its CSS Stringify Output
Weaknesses CWE-79
References
Metrics cvssV3_1

{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-04-24T02:27:47.719Z

Updated: 2026-04-24T16:23:41.198Z

Reserved: 2026-04-20T14:01:46.670Z

Link: CVE-2026-41305

cve-icon Vulnrichment

Updated: 2026-04-24T16:23:25.257Z

cve-icon NVD

Status : Deferred

Published: 2026-04-24T03:16:11.547

Modified: 2026-04-24T17:16:21.500

Link: CVE-2026-41305

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-04-24T02:27:47Z

Links: CVE-2026-41305 - Bugzilla