Soup Sieve is a CSS selector library designed to be used with Beautiful Soup 4. Prior to 2.10, matching a developer-authored selector that places the general sibling combinator inside :has() repeatedly scans each candidate element's following siblings when the right-hand side is absent, producing quadratic work on attacker-controlled HTML. Applications that evaluate a fixed selector such as div:has(a ~ b) over untrusted markup can have a worker occupied for minutes by a small document, while the adjacent sibling form and trusted-only document processing are not affected in the same way. This issue is fixed in version 2.10.
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Fixes

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History

Thu, 12 Nov 2026 17:15:00 +0000

Type Values Removed Values Added
Description Soup Sieve is a CSS selector library designed to be used with Beautiful Soup 4. Prior to 2.10, matching a developer-authored selector that places the general sibling combinator inside :has() repeatedly scans each candidate element's following siblings when the right-hand side is absent, producing quadratic work on attacker-controlled HTML. Applications that evaluate a fixed selector such as div:has(a ~ b) over untrusted markup can have a worker occupied for minutes by a small document, while the adjacent sibling form and trusted-only document processing are not affected in the same way. This issue is fixed in version 2.10.
Title Soup Sieve: General sibling combinator inside :has() matches untrusted HTML in quadratic time
Weaknesses CWE-400
CWE-407
References
Metrics cvssV4_0

{'score': 6.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-11-12T17:09:14.205Z

Reserved: 2026-11-10T20:07:44.957Z

Link: CVE-2026-126192

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-11-12T17:17:32.793

Modified: 2026-11-12T17:17:32.793

Link: CVE-2026-126192

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses