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Fencer Intel
medium 5.3

CVE-2026-126193 json

Soup Sieve: Uncontrolled recursion in Soup Sieve CSS parser lets nested pseudo-class selectors exhaust the Python call stack

published 9d ago modified 20h ago also EUVD-2026-124559 , GHSA-7g44-g9rc-x53w

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository facelessuser/soupsieve. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
—
no EPSS score yet
public exploits
0
none known

Summary

Soup Sieve is a CSS selector library for Beautiful Soup. From 0.4 until 3.0, deeply nested CSS pseudo-class selectors can cause recursive parsing to exceed Python’s recursion limit and raise  RecursionError . Applications accepting untrusted selectors may experience failure of the affected request or task if the exception is not handled. The demonstrated behavior is recoverable and does not establish an interpreter crash or persistent service-wide denial of service. This vulnerability is fixed in version 3.0.

Patch / fix

  • pypi soupsieve 3.0

Is CVE-2026-126193 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected packages

ecosystem package affected fixed in
pypi soupsieve
>=0.4, <=2.10
3.0

Affected products

  • facelessuser soupsieve

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of facelessuser/soupsieve published their own advisory on GitHub. Reviewed sources take precedence over it.