CVE-2026-49477
HIGHSoup Sieve: Regular Expression Denial of Service (ReDoS) in soupsieve Selector Parser
Title source: cnaDescription
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.
References (3)
Core 3
Core References
X_Refsource_Confirm x_refsource_confirm
https://github.com/facelessuser/soupsieve/security/advisories/GHSA-836r-79rf-4m37
X_Refsource_Misc x_refsource_misc
https://github.com/facelessuser/soupsieve/commit/eb4397618709186c109400448c6043b728217dc3
X_Refsource_Misc x_refsource_misc
https://github.com/facelessuser/soupsieve/releases/tag/2.8.4
Scores
CVSS v3
7.5
EPSS
0.0052
EPSS Percentile
41.4%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
yes
Technical Impact
partial
Details
CWE
CWE-1333
CWE-400
Status
published
Products (2)
facelessuser/soup_sieve
< 2.8.4
facelessuser/soupsieve
< 2.8.4
Published
Jul 14, 2026
Tracked Since
Jul 15, 2026