CVE-2026-126190 (CVSS 7.5)

Description

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.

Is your site exposed to CVE-2026-126190?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-407 CWE-407

References

Other References

https://github.com/facelessuser/soupsieve/commit/ff1a5ce7e5addc31626d7b6053511fecdb4f6320 https://github.com/facelessuser/soupsieve/pull/351 https://github.com/facelessuser/soupsieve/releases/tag/4.0 https://github.com/facelessuser/soupsieve/security/advisories/GHSA-mmhr-3c5m-f64f

Frequently Asked Questions

What is CVE-2026-126190? +

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. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-126190? +

CVE-2026-126190 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

How do I check if I'm vulnerable to CVE-2026-126190? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-3276

unicodedata.normalize() can take excessive CPU time when processing specially crafted Unicode input containing long runs of combining characters with alternating …

CVE-2026-40476

graphql-go is a Go implementation of GraphQL. In versions 15.31.4 and below, the OverlappingFieldsCanBeMerged validation rule performs O(n²) pairwise comparisons …

CVE-2026-43967

Inefficient Algorithmic Complexity vulnerability in absinthe-graphql absinthe allows unauthenticated denial of service via quadratic fragment-name uniqueness validation. 'Elixir.Absinthe.Phase.Document.Validation.UniqueFragmentNames':run/2 iterates over …

CVE-2026-58059

In Bouncy Castle for Java before 1.85, Quadratic-time escaping when stringifying X.500 distinguished names. This issue also affects Bouncy Castle …

CVE-2026-16762

An attacker able to supply a crafted XML document to an application using QXmlStreamReader can cause disproportionate CPU consumption during …

CVE-2026-110688

Cpanel::JSON::XS versions from 4.51 before 4.80 for Perl allow quadratic CPU use by revalidating the remaining buffer per value in …