Vulnerability 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 contains a regular expression vulnerable to catastrophic backtracking when processing an attribute selector with an unterminated quoted value in soupsieve/css_parser.py, allowing an attacker who can supply untrusted CSS selector strings to soupsieve.compile() or Beautiful Soup .select() / .select_one() to cause CPU exhaustion and denial of service. This issue is fixed in version 2.8.4.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Facelessuser | Soup Sieve | < 2.8.4 |
Related Weaknesses (CWE)
References
- https://github.com/facelessuser/soupsieve/commit/eb4397618709186c109400448c6043bPatch
- https://github.com/facelessuser/soupsieve/releases/tag/2.8.4Release Notes
- https://github.com/facelessuser/soupsieve/security/advisories/GHSA-836r-79rf-4m3ExploitVendor Advisory
- https://github.com/facelessuser/soupsieve/security/advisories/GHSA-836r-79rf-4m3ExploitVendor Advisory
FAQ
What is CVE-2026-49477?
CVE-2026-49477 is a vulnerability with a CVSS score of 7.5 (HIGH). 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 contains a regular expression vulnerable to catastrophic backtracki...
How severe is CVE-2026-49477?
CVE-2026-49477 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-49477?
Check the references section above for vendor advisories and patch information. Affected products include: Facelessuser Soup Sieve.