Vulnerability · Published Jul 14, 2026 · Assigned by GitHub_M
CVE-2026-49477Soup Sieve: Regular Expression Denial of Service (ReDoS) in soupsieve Selector Parser
High 7.5
In plain English
A high-severity uncontrolled resource consumption in soupsieve from facelessuser. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 51% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | soupsieve | no fix listed | DEBIAN-CVE-2026-49477 |
| Debian:13 | soupsieve | no fix listed | DEBIAN-CVE-2026-49477 |
| Debian:14 | soupsieve | 2.8.4-1 | DEBIAN-CVE-2026-49477 |
| PyPI | soupsieve | 2.8.4 | GHSA-836r-79rf-4m37 |
| PyPI | soupsieve | 2.8.4 | PYSEC-2026-3072 |
| Ubuntu:22.04:LTS | soupsieve | no fix listed | UBUNTU-CVE-2026-49477 |
| Ubuntu:24.04:LTS | soupsieve | no fix listed | UBUNTU-CVE-2026-49477 |
| Ubuntu:26.04:LTS | soupsieve | no fix listed | UBUNTU-CVE-2026-49477 |
| Ubuntu:26.10 | soupsieve | no fix listed | UBUNTU-CVE-2026-49477 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| facelessuser | soupsieve | < 2.8.4 |
Weakness: CWE-400, CWE-1333 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H