CVE-2026-49477
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 3.1
- 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS
- 0.6% chance of exploitation in the next 30 days; higher than 50% of CVEs (scores of 2026-10-25)
- CWEs
- CWE-400, CWE-1333
- Published
- Modified
- Record from
- the NVD, synced
Affected
- facelessuser:soup_sieve
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-836r-79rf-4m37 | PyPI | soupsieve | <2.8.4 | 2.8.4 |
| PYSEC-2026-3072 | PyPI | soupsieve | <2.8.4 | 2.8.4 |
References
- https://github.com/facelessuser/soupsieve/commit/eb4397618709186c109400448c6043b728217dc3
- https://github.com/facelessuser/soupsieve/releases/tag/2.8.4
- https://github.com/facelessuser/soupsieve/security/advisories/GHSA-836r-79rf-4m37
- https://github.com/facelessuser/soupsieve/security/advisories/GHSA-836r-79rf-4m37