CVE-2025-69534

Description

Python-Markdown version 3.8 contain a vulnerability where malformed HTML-like sequences can cause html.parser.HTMLParser to raise an unhandled AssertionError during Markdown parsing. Because Python-Markdown does not catch this exception, any application that processes attacker-controlled Markdown may crash. This enables remote, unauthenticated Denial of Service in web applications, documentation systems, CI/CD pipelines, and any service that renders untrusted Markdown. The issue was acknowledged by the vendor and fixed in version 3.8.1. This issue causes a remote Denial of Service in any application parsing untrusted Markdown, and can lead to Information Disclosure through uncaught exceptions.

References

https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-69534.json

https://github.com/Python-Markdown/markdown/issues/1534

https://github.com/Python-Markdown/markdown/actions/runs/15736122892

https://github.com/Python-Markdown/markdown

https://bugzilla.redhat.com/show_bug.cgi?id=2444839

https://access.redhat.com/security/cve/CVE-2025-69534

https://access.redhat.com/errata/RHSA-2026:9742

https://access.redhat.com/errata/RHSA-2026:20677

https://access.redhat.com/errata/RHSA-2026:20676

https://access.redhat.com/errata/RHSA-2026:20674

https://access.redhat.com/errata/RHSA-2026:19366

https://access.redhat.com/errata/RHSA-2026:19155

https://access.redhat.com/errata/RHSA-2026:14874

https://access.redhat.com/errata/RHSA-2026:14873

https://access.redhat.com/errata/RHSA-2026:14835

https://access.redhat.com/errata/RHSA-2026:13826

https://access.redhat.com/errata/RHSA-2026:13512

https://access.redhat.com/errata/RHSA-2026:13508

https://access.redhat.com/errata/RHSA-2026:10184

http://www.openwall.com/lists/oss-security/2026/03/06/4

Details

Source: Mitre, NVD

Risk Information

CVSS v2

CVSS v3

CVSS v4

EPSS