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Description

Soup Sieve is a CSS selector library designed to be used with Beautiful Soup 4. Prior to 2.8.4, the CSS selector parser in soupsieve allocates unbounded memory when compiling large comma-separated selector lists, allowing an attacker who can supply a crafted selector string to soupsieve.compile() or Beautiful Soup .select() / .select_one() to allocate hundreds of megabytes of heap memory from a relatively small input and cause denial of service. This issue is fixed in version 2.8.4.

PUBLISHED Reserved 2026-05-30 | Published 2026-07-14 | Updated 2026-07-14 | Assigner GitHub_M




HIGH: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem types

CWE-400: Uncontrolled Resource Consumption

CWE-770: Allocation of Resources Without Limits or Throttling

Product status

< 2.8.4
affected

References

github.com/...psieve/security/advisories/GHSA-2wc2-fm75-p42x

github.com/...ommit/28108ab805818c832d9568142a99844fd95a0d39

github.com/facelessuser/soupsieve/releases/tag/2.8.4

cve.org (CVE-2026-49476)

nvd.nist.gov (CVE-2026-49476)

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