postcss-selector-parser allows denial of service through uncontrolled AST recursion
Published 26 May 2026 · Updated 10 Sept 2026
Affected packages
- Affected
- >=6.1.0 <6.1.3
- Fixed in
- 6.1.3
npm install postcss-selector-parser@6.1.3- Affected
- >=7.1.0 <7.1.3
- Fixed in
- 7.1.3
npm install postcss-selector-parser@7.1.3Details
A vulnerability was determined in postcss-selector-parser before 6.1.3 and 7.1.1. Affected is the function toString of the file src/selectors/container.js of the component AST Serialization. Executing a manipulation can lead to uncontrolled recursion. It is possible to launch the attack remotely. The exploit has been publicly disclosed and may be utilized. The vendor explains, that according to his definition "DoS on server-side on user-generated CSS is low risk for us (since most users compile own CSS with PostCSS)."
Is GHSA-w9m9-85wc-3x92 in any of your client repos?
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References
- Advisorynvd.nist.gov/vuln/detail/CVE-2026-9358
- Linkgithub.com/postcss/postcss-selector-parser/commit/5bc698cef66f8abd12610dc623e5d67cbc0f869d
- Linkgithub.com/postcss/postcss-selector-parser/commit/e37c5b0b785b165e27508d2489fdec8e0f18b10a
- Linkgist.github.com/bx33661/581e3a38134601c04e19b4dfc9b459b9
- Packagegithub.com/postcss/postcss-selector-parser
- Linkgithub.com/postcss/postcss-selector-parser/releases/tag/6.1.3
- Linkgithub.com/postcss/postcss-selector-parser/releases/tag/7.1.3
- Linkvuldb.com/cve/CVE-2026-9358
- Linkvuldb.com/submit/813080
- Linkvuldb.com/vuln/365321
- Linkvuldb.com/vuln/365321/cti
Advisory data from OSV.dev (opens OSV.dev in a new tab), refreshed daily.