chore(deps): update dependency postcss to v8.5.10 [security]

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
postcss (source)	8.4.19 → 8.5.10

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PostCSS line return parsing error

CVE-2023-44270 / GHSA-7fh5-64p2-3v2j

More information

Details

An issue was discovered in PostCSS before 8.4.31. It affects linters using PostCSS to parse external Cascading Style Sheets (CSS). There may be \r discrepancies, as demonstrated by @font-face{ font:(\r/*);} in a rule.

This vulnerability affects linters using PostCSS to parse external untrusted CSS. An attacker can prepare CSS in such a way that it will contains parts parsed by PostCSS as a CSS comment. After processing by PostCSS, it will be included in the PostCSS output in CSS nodes (rules, properties) despite being originally included in a comment.

Severity

• CVSS Score: 5.3 / 10 (Medium)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

References

• https://nvd.nist.gov/vuln/detail/CVE-2023-44270
• https://github.com/postcss/postcss/commit/58cc860b4c1707510c9cd1bc1fa30b423a9ad6c5
• https://github.com/postcss/postcss/blob/main/lib/tokenize.js#L25
• https://github.com/postcss/postcss/releases/tag/8.4.31
• https://github.com/github/advisory-database/issues/2820
• https://lists.debian.org/debian-lts-announce/2024/12/msg00025.html
• https://github.com/advisories/GHSA-7fh5-64p2-3v2j

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

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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).

---

Release Notes

postcss/postcss (postcss)

v8.5.10

Compare Source

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

v8.5.9

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• Speed up source map encoding paring in case of the error.

v8.5.8

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• Fixed Processor#version.

v8.5.7

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• Improved source map annotation cleaning performance (by CodeAnt AI).

v8.5.6

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• Fixed ContainerWithChildren type discriminating (by @​Goodwine).

v8.5.5

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• Fixed package.json→exports compatibility with some tools (by @​JounQin).

v8.5.4

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• Fixed Parcel compatibility issue (by @​git-sumitchaudhary).

v8.5.3

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• Added more details to Unknown word error (by @​hiepxanh).
• Fixed types (by @​romainmenke).
• Fixed docs (by @​catnipan).

v8.5.2

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• Fixed end position of rules with semicolon (by @​romainmenke).

v8.5.1

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• Fixed declaration parsing performance (by @​homanp).

v8.5.0: 8.5 “Duke Alloces”

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PostCSS 8.5 brought API to work better with non-CSS sources like HTML, Vue.js/Svelte sources or CSS-in-JS.

@​romainmenke during his work on Stylelint added Input#document in additional to Input#css.

root.source.input.document //=> "<p>Hello</p>
                           //    <style>
                           //    p {
                           //      color: green;
                           //    }
                           //    </style>"
root.source.input.css      //=> "p {
                           //      color: green;
                           //    }"

Thanks to Sponsors

This release was possible thanks to our community.

If your company wants to support the sustainability of front-end infrastructure or wants to give some love to PostCSS, you can join our supporters by:

• Tidelift with a Spotify-like subscription model supporting all projects from your lock file.
• Direct donations at GitHub Sponsors or Open Collective.

v8.4.49

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• Fixed custom syntax without source.offset (by @​romainmenke).

v8.4.48

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• Fixed position calculation in error/warnings methods (by @​romainmenke).

v8.4.47

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• Removed debug code.

v8.4.46

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• Fixed Cannot read properties of undefined (reading 'before').

v8.4.45

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• Removed unnecessary fix which could lead to infinite loop.

v8.4.44

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• Another way to fix markClean is not a function error.

v8.4.43

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• Fixed markClean is not a function error.

v8.4.42

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• Fixed CSS syntax error on long minified files (by @​varpstar).

v8.4.41

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• Fixed types (by @​nex3 and @​querkmachine).
• Cleaned up RegExps (by @​bluwy).

v8.4.40

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• Moved to getter/setter in nodes types to help Sass team (by @​nex3).

v8.4.39

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• Fixed CssSyntaxError types (by @​romainmenke).

v8.4.38

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• Fixed endIndex: 0 in errors and warnings (by @​romainmenke).

v8.4.37

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• Fixed original.column are not numbers error in another case.

v8.4.36

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• Fixed original.column are not numbers error on broken previous source map.

v8.4.35

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• Avoid ! in node.parent.nodes type.
• Allow to pass undefined to node adding method to simplify types.

v8.4.34

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• Fixed AtRule#nodes type (by Tim Weißenfels).
• Cleaned up code (by Dmitry Kirillov).

v8.4.33

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• Fixed NoWorkResult behavior difference with normal mode (by Romain Menke).
• Fixed NoWorkResult usage conditions (by @​ahmdammarr).

v8.4.32

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• Fixed postcss().process() types (by Andrew Ferreira).

v8.4.31

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• Fixed \r parsing to fix CVE-2023-44270.

v8.4.30

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• Improved source map performance (by Romain Menke).

v8.4.29

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• Fixed Node#source.offset (by Ido Rosenthal).
• Fixed docs (by Christian Oliff).

v8.4.28

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• Fixed Root.source.end for better source map (by Romain Menke).
• Fixed Result.root types when process() has no parser.

v8.4.27

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• Fixed Container clone methods types.

v8.4.26

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• Fixed clone methods types.

v8.4.25

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• Improve stringify performance (by Romain Menke).
• Fixed docs (by @​vikaskaliramna07).

v8.4.24

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• Fixed Plugin types.

v8.4.23

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• Fixed warnings in TypeDoc.

v8.4.22

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• Fixed TypeScript support with node16 (by Remco Haszing).

v8.4.21

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• Fixed Input#error types (by Aleks Hudochenkov).

v8.4.20

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• Fixed source map generation for childless at-rules like @layer.

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