CVE-2026-126191
Soup Sieve: Exponential ReDoS in selector compilation via \9-run in CSS_ESCAPES/IDENTIFIER
Soup Sieve is a CSS selector library designed to be used with Beautiful Soup 4. Prior to 3.0, the CSS_ESCAPES and IDENTIFIER regular-expression subpatterns can backtrack exponentially on runs of ambiguous digit escapes in an attribute-name or tag position of an otherwise valid selector. The failure occurs during selector compilation through soupsieve.compile() or Beautiful Soup select() before SELECTOR_LIMIT is applied, so an application that accepts untrusted selector strings can have a worker stalled by a short input. This issue is fixed in version 3.0.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| soupsieve facelessuser |
< 3.0 (affected) | CNA: GitHub_M |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 7.5 high |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | CNA: GitHub_M |
| 3.1 / 7.5 high |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | NVD: [email protected] |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://github.com/facelessuser/soupsieve/security/advisories/GHSA-6655-6qjp-jx7xCNA: GitHub_M · x_refsource_CONFIRM
- https://github.com/facelessuser/soupsieve/pull/300CNA: GitHub_M · x_refsource_MISC
- https://github.com/facelessuser/soupsieve/commit/dbfa2854ff31a863326bd6660d4e55c6f068db9eCNA: GitHub_M · x_refsource_MISC
- https://github.com/facelessuser/soupsieve/releases/tag/3.0CNA: GitHub_M · x_refsource_MISC
- https://github.com/facelessuser/soupsieve/commit/dbfa2854ff31a863326bd6660d4e55c6f068db9e[email protected]
- https://github.com/facelessuser/soupsieve/pull/300[email protected]
- https://github.com/facelessuser/soupsieve/releases/tag/3.0[email protected]
- https://github.com/facelessuser/soupsieve/security/advisories/GHSA-6655-6qjp-jx7x[email protected]
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