Application crash via deeply nested selectors
Published May 24, 2026 · Updated May 24, 2026
Uncontrolled recursion in postcss-selector-parser 7.1.1 and earlier allows remote attackers to crash CSS-processing applications. Container and pseudo-node serialization recursively stringifies nested selector children without enforcing a depth limit, exhausting the JavaScript call stack. Remote exposure exists only when an integrating application processes attacker-controlled selector strings; the library provides no network service itself.
Summary
What happened
Uncontrolled recursion in postcss-selector-parser 7.1.1 and earlier allows remote attackers to crash CSS-processing applications. Container and pseudo-node serialization recursively stringifies nested selector children without enforcing a depth limit, exhausting the JavaScript call stack. Remote exposure exists only when an integrating application processes attacker-controlled selector strings; the library provides no network service itself.
The record
- CVE
- CVE-2026-9358
- Published
- May 24, 2026
- Updated
- May 24, 2026
- Vendor
- PostCSS
- Product
- PostCSS
- Classifications
- CWE-404, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 24, 2026CVE publishedPublication date reported by the CVE source.
- May 24, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=7.1.0
- Affected versionversion=7.1.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Deeply nested selector denial-of-service proof of conceptproof of concept · unverified
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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