Python CPython up to 3.13.x html.parser.HTMLParser redos

CVSS Meta Temp Score
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CTI Interest Score
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4.2$0-$5k0.00

Summaryinfo

A vulnerability was found in Python CPython up to 3.13.x and classified as problematic. Affected by this vulnerability is the function html.parser.HTMLParser. The manipulation results in redos. This vulnerability was named CVE-2025-6069. The attack may be performed from remote. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Python CPython up to 3.13.x. Affected is the function html.parser.HTMLParser. The manipulation with an unknown input leads to a redos vulnerability. CWE is classifying the issue as CWE-1333. The product uses a regular expression with an inefficient, possibly exponential worst-case computational complexity that consumes excessive CPU cycles. This is going to have an impact on availability. CVE summarizes:

The html.parser.HTMLParser class had worse-case quadratic complexity when processing certain crafted malformed inputs potentially leading to amplified denial-of-service.

The weakness was presented by sw0rd1ight as 135462. The advisory is shared for download at github.com. This vulnerability is traded as CVE-2025-6069 since 06/13/2025. The exploitability is told to be easy. It is possible to launch the attack remotely. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1449.003.

The vulnerability scanner Nessus provides a plugin with the ID 241510 (openSUSE 15 Security Update : python39 (SUSE-SU-2025:02232-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 3.14.0 eliminates this vulnerability. Applying the patch 4455cbabf991e202185a25a631af206f60bbc949 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (241510), EUVD (EUVD-2025-18496) and CERT Bund (WID-SEC-2025-1470). Once again VulDB remains the best source for vulnerability data.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Fedora Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • RESF Rocky Linux
  • Dell Avamar
  • Open Source Python
  • Dell NetWorker
  • Dell Secure Connect Gateway

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.3
VulDB Meta Temp Score: 4.2

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 4.3
CNA Vector (PSF): 🔒

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Redos
CWE: CWE-1333 / CWE-400 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 241510
Nessus Name: openSUSE 15 Security Update : python39 (SUSE-SU-2025:02232-1)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: CPython 3.14.0
Patch: 4455cbabf991e202185a25a631af206f60bbc949

Timelineinfo

06/13/2025 CVE reserved
06/17/2025 +4 days Advisory disclosed
06/17/2025 +0 days VulDB entry created
12/20/2025 +186 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: 135462
Researcher: sw0rd1ight
Status: Confirmed

CVE: CVE-2025-6069 (🔒)
GCVE (CVE): GCVE-0-2025-6069
GCVE (VulDB): GCVE-100-312708
EUVD: 🔒
CERT Bund: WID-SEC-2025-1470 - Python (CPython): Schwachstelle ermöglicht Denial of Service

Entryinfo

Created: 06/17/2025 16:46
Updated: 12/20/2025 23:49
Changes: 06/17/2025 16:46 (69), 06/17/2025 17:29 (1), 07/09/2025 01:24 (2), 08/17/2025 17:00 (7), 11/01/2025 09:10 (1), 12/20/2025 23:49 (1)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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