CVE-2026-49477
Soup Sieve: Regular Expression Denial of Service (ReDoS) in soupsieve Selector Parser
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.
INFO
Published Date :
July 14, 2026, 9:17 p.m.
Last Modified :
July 28, 2026, 3:48 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update Soup Sieve to version 2.8.4.
- Use newer library versions.
Public PoC/Exploit Available at Github
CVE-2026-49477 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-49477.
| URL | Resource |
|---|---|
| https://github.com/facelessuser/soupsieve/commit/eb4397618709186c109400448c6043b728217dc3 | Patch |
| https://github.com/facelessuser/soupsieve/releases/tag/2.8.4 | Release Notes |
| https://github.com/facelessuser/soupsieve/security/advisories/GHSA-836r-79rf-4m37 | Exploit Vendor Advisory |
| https://github.com/facelessuser/soupsieve/security/advisories/GHSA-836r-79rf-4m37 | Exploit Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-49477 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-49477
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
All Public RunWhen Helm Charts - Managed by terraform
Shell Dockerfile Go Template
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-49477 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-49477 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Jul. 28, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:facelessuser:soup_sieve:*:*:*:*:*:beautiful_soup:*:* versions up to (excluding) 2.8.4 Added Reference Type GitHub, Inc.: https://github.com/facelessuser/soupsieve/commit/eb4397618709186c109400448c6043b728217dc3 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/facelessuser/soupsieve/releases/tag/2.8.4 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/facelessuser/soupsieve/security/advisories/GHSA-836r-79rf-4m37 Types: Exploit, Vendor Advisory Added Reference Type CISA-ADP: https://github.com/facelessuser/soupsieve/security/advisories/GHSA-836r-79rf-4m37 Types: Exploit, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 21, 2026
Action Type Old Value New Value Added Reference https://github.com/facelessuser/soupsieve/security/advisories/GHSA-836r-79rf-4m37 Added SSVC {'id': 'CVE-2026-49477', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-21T14:49:25.096784Z'} -
New CVE Received by [email protected]
Jul. 14, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'facelessuser', 'product': 'soupsieve', 'versions': [{'status': 'affected', 'version': '< 2.8.4'}]}] Added 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-400 Added CWE CWE-1333 Added Reference https://github.com/facelessuser/soupsieve/commit/eb4397618709186c109400448c6043b728217dc3 Added Reference https://github.com/facelessuser/soupsieve/releases/tag/2.8.4 Added Reference https://github.com/facelessuser/soupsieve/security/advisories/GHSA-836r-79rf-4m37