# CVE-2026-41305: 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.

- Web page: https://patchblox.com/security/cve/CVE-2026-41305
- Priority: Routine
- CVSS: 6.1 (Moderate)
- EPSS: 0.0021
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Apr 24, 2026
- Weakness: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-41305

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | node-postcss Debian 14 | 8.5.12+~cs9.3.32-1 | [DEBIAN-CVE-2026-41305](https://patchblox.com/security/data/fix/linux/debian-cve-2026-41305.md) | May 15, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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