Inefficient Algorithmic Complexity Affecting postcss-selector-parser package, versions <7.1.6
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JS-POSTCSSSELECTORPARSER-20510276
- published5 Oct 2026
- disclosed2 Oct 2026
- creditUnknown
Introduced: 2 Oct 2026
NewCVE-2026-104844 (opens in a new tab)How to fix?
Upgrade postcss-selector-parser to version 7.1.6 or higher.
Overview
Affected versions of this package are vulnerable to Inefficient Algorithmic Complexity via the uniqs helper and index-membership checks in src/parser.js when parsing flat selectors (e.g. .a.a.a...) containing a large number of class or ID tokens. The original implementation uses Array.indexOf inside a filter callback and repeated linear scans of the hasClass/hasId arrays, producing quadratic time complexity proportional to the number of tokens. An attacker who can supply selector input to the parser can trigger CPU exhaustion by providing a long flat selector, pinning a CPU core and causing the process to become unresponsive.