CVSS 4.0
6.3 mediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:NCVE-2026-126192 Soup Sieve: General sibling combinator inside :has() matches untrusted HTML in quadratic time
Medium (6.3) in facelessuser soupsieve. EPSS 0.5% estimated probability of exploitation activity in the next 30 days. Fixed in soupsieve 2.10.0.
On this page
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.
Severity
- EPSS
- 0.5% estimated probability of exploitation activity in the next 30 days; 42nd percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
- CISA's assessment (SSVC)
- Exploitation: PoC · Automatable: no · Technical impact: partial, assessed 2026-11-13. From CISA's Vulnrichment in the CVE List: whether it is exploited, whether exploiting it can be automated, and how much control it gives.
- Published
- Modified
- Assigned by
- GitHub_M (CNA)
- NVD analysis
- Awaiting analysis
- Record from
- the NVD, synced
Ask an AI about this CVE
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Explain CVE-2026-126192 for an engineer deciding whether to act. Use https://cve.bz/api/public/cves/CVE-2026-126192?via=ask-ai-copy and https://cve.bz/cve/CVE-2026-126192?via=ask-ai-copy as the source of truth: what is affected and which versions fix it, whether it is in CISA KEV, public exploits, and its EPSS (an internet-wide 30-day estimate of exploitation activity, not a forecast for my systems). If they give no fixed versions, use the CVE record https://cveawg.mitre.org/api/cve/CVE-2026-126192 or the vendor advisory, not third-party mirrors. Tell me how to check whether I am affected and how to verify a fix. Cite the sources and say where they are uncertain.Opens a third-party assistant; its answer is its own, not cve.bz's. The prompt holds only this CVE's id and public links.
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Affected
Versions
From the CNA's record in the CVE List.
| Product | Affected |
|---|---|
| facelessuser soupsieve | < 2.10 |
Fix and patched versions
soupsieve(PyPI): fixed in 2.10.0
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-4j63-6c4x-wfg4 | PyPI | soupsieve | <2.10.0 | 2.10.0 |
Linux distributions
| Distribution | Release | Package | Fixed in | Advisory |
|---|---|---|---|---|
| Ubuntu | 20.04:LTS, 22.04:LTS, 24.04:LTS and 2 more | soupsieve | no fix listed | UBUNTU-CVE-2026-126192 |
From the distributions' data via OSV.dev: Ubuntu Security Notices © Canonical Ltd., CC BY-SA 4.0. Modified: reformatted and linked to CVE records. Credits. On the distributions' own pages: Ubuntu.
Attack patterns (CAPEC)
- CAPEC-147 XML Ping of the Death Likelihood: Low · Severity: Medium
- CAPEC-227 Sustained Client Engagement
- CAPEC-492 Regular Expression Exponential Blowup
The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.