CVSS 3.1
7.5 highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HCVE-2026-126190 Soup Sieve: Polynomial-time denial of service in the descendant combinator
High (7.5) in facelessuser soupsieve. EPSS 0.5% estimated probability of exploitation activity in the next 30 days. Fixed in soupsieve 4.0.0.
On this page
Soup Sieve is a CSS selector library designed to be used with Beautiful Soup 4. Prior to 4.0, Soup Sieve repeatedly walks the same ancestors while matching descendant combinators, and each additional descendant combinator raises the polynomial degree of the work on deeply nested attacker-influenced HTML or XML. Applications using selectors such as section div div through select(), select_one(), or Beautiful Soup CSS APIs against untrusted documents can have a worker occupied for seconds or minutes, while trusted-only document processing is not affected. Selectors compiled with NOCACHE continue to use the old uncached behavior. This issue is fixed in version 4.0.
Severity
- EPSS
- 0.5% estimated probability of exploitation activity in the next 30 days; 46th percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
- CISA's assessment (SSVC)
- Exploitation: none · Automatable: yes · 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.
- CWE
- CWE-407 Inefficient Algorithmic Complexity
- 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-2026-126190 for an engineer deciding whether to act. Use https://cve.bz/api/public/cves/CVE-2026-126190?via=ask-ai-copy and https://cve.bz/cve/CVE-2026-126190?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-2026-126190 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 | < 4.0 |
Fix and patched versions
soupsieve(PyPI): fixed in 4.0.0
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-mmhr-3c5m-f64f | PyPI | soupsieve | <4.0.0 | 4.0.0 |
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-2026-126190 |
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.