CVE-2026-49476: Facelessuser Soup Sieve

High severity, CVSS 7.5. EPSS: 0.6% chance of exploitation in the next 30 days.

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.

Affected products

• Facelessuser Soup Sieve: before 2.8.4 (fixed in 2.8.4)

Published 2026-07-14. Last modified 2026-07-28.