CVE-2026-49477
High
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.
SeverityHigh
CVSS7.5
Exploit probability—
ProductFacelessuser Soup Sieve
PublishedJul 14, 2026
First seenJul 14, 2026
How to fix
Update
- facelessuser soup_sieve2.8.4 or later
- soupsieve2.8.4 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| facelessuser soup_sieve | v < 2.8.4 | 2.8.4 |
| soupsievePyPI | v < 2.8.4 | 2.8.4 |
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