CVE-2026-49477

HIGH 7.5

Soup Sieve: Regular Expression Denial of Service (ReDoS) in soupsieve Selector Parser

CVSS Score

7.5

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-400 CWE-1333
Vendor	facelessuser
Product	soupsieve
Published	Jul 14, 2026

Stay Ahead of the Next One

Get instant alerts for facelessuser soupsieve

Be the first to know when new high vulnerabilities affecting facelessuser soupsieve are published — delivered to Slack, Telegram or Discord.

Get Free Alerts → Free · No credit card · 60 sec setup

CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Affected Versions

facelessuser / soupsieve

< 2.8.4

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/facelessuser/soupsieve/security/advisories/GHSA-836r-79rf-4m37 github.com: https://github.com/facelessuser/soupsieve/commit/eb4397618709186c109400448c6043b728217dc3 github.com: https://github.com/facelessuser/soupsieve/releases/tag/2.8.4