Bump dependency postcss to v8.5.10 [SECURITY]

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
postcss (source)	8.5.9 → 8.5.10

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

CVE-2026-41305 / GHSA-qx2v-qp2m-jg93

More information

Details

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

Summary

PostCSS v8.5.5 (latest) does 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.

Proof of Concept

const postcss = require('postcss');

// Parse user CSS and re-stringify for page embedding
const userCSS = 'body { content: "</style><script>alert(1)</script><style>"; }';
const ast = postcss.parse(userCSS);
const output = ast.toResult().css;
const html = `<style>${output}</style>`;

console.log(html);
// <style>body { content: "</style><script>alert(1)</script><style>"; }</style>
//
// Browser: </style> closes the style tag, <script> executes

Tested output (Node.js v22, postcss v8.5.5):

Input: body { content: "</style><script>alert(1)</script><style>"; }
Output: body { content: "</style><script>alert(1)</script><style>"; }
Contains </style>: true

Impact

Impact non-bundler use cases since bundlers for XSS on their own. Requires some PostCSS plugin to have malware code, which can inject XSS to website.

Suggested Fix

Escape </style in all stringified output values:

output = output.replace(/<\/(style)/gi, '<\\/$1');

Credits

Discovered and reported by Sunil Kumar (@​TharVid)

Severity

• CVSS Score: 6.1 / 10 (Medium)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

References

• https://github.com/postcss/postcss/security/advisories/GHSA-qx2v-qp2m-jg93
• https://nvd.nist.gov/vuln/detail/CVE-2026-41305
• https://github.com/postcss/postcss/releases/tag/8.5.10
• https://github.com/advisories/GHSA-qx2v-qp2m-jg93

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

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Release Notes

postcss/postcss (postcss)

v8.5.10

Compare Source

• Fixed XSS via unescaped </style> in non-bundler cases (by @​TharVid).

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[github-actions]

☀️   Quality Monitor

Tests

   🚀   Integration Tests: ✅ successful — 10 passed
   ⛔   Architecture Tests: ✅ successful — 15 passed

Coverage for New Code

   〰️   Line Coverage: 100.00% — perfect 🎉
   ➰   Branch Coverage: 100.00% — perfect 🎉

Coverage for Whole Project

   〰️   Line Coverage: 84.21% — 3 missed lines
   ➰   Branch Coverage: 100.00% — perfect 🎉

Style

     CheckStyle: No warnings
     PMD: No warnings
   ☕   Java Compiler: No warnings

Bugs

     SpotBugs: No bugs
   🐛   Error Prone: No bugs

API Problems

   🚫   Revapi: No warnings

Vulnerabilities

   🛡️   OWASP Dependency Check: 207 vulnerabilities — error: 17, high: 54, normal: 125, low: 11

Software Metrics

   🌀   Cyclomatic Complexity: 8 (total)
   💭   Cognitive Complexity: 0 (total)
   ➿   N-Path Complexity: 8 (total)
   📏   Lines of Code: 104 (total)
   📝   Non Commenting Source Statements: 25 (total)
   🔗   Class Cohesion: 6.67% (maximum)
   ⚖️   Weight of Class: 20.00% (maximum)

🚦 Quality Gates

Overall Status: ✅ SUCCESS

✅ Passed Gates

• ✅ Overall Tests Success Rate: 100.00 >= 100.00
• ✅ Potential Bugs in Whole Project: 0.00 <= 0.00
• ✅ Style Violation in Whole Project: 0.00 <= 0.00

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