What’s Vulnerable › Vulnerabilities
CVE-2025-69534
- Severity: high (CVSS 7.5 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.6% probability of exploitation in the next 30 days
- Public exploit or detection template: yes
- Published: 2026-03-05 · updated 2026-09-07
- Weakness: CWE-400
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.
Affected products
References
- https://github.com/Python-Markdown/markdown
- https://github.com/Python-Markdown/markdown/actions/runs/15736122892
- https://github.com/Python-Markdown/markdown/issues/1534
- http://www.openwall.com/lists/oss-security/2026/03/06/4
- https://access.redhat.com/errata/RHSA-2026:10184
- https://access.redhat.com/errata/RHSA-2026:13508
- https://access.redhat.com/errata/RHSA-2026:13512
- https://access.redhat.com/errata/RHSA-2026:13826
- https://access.redhat.com/errata/RHSA-2026:14835
- https://access.redhat.com/errata/RHSA-2026:14873
- https://access.redhat.com/errata/RHSA-2026:14874
- https://access.redhat.com/errata/RHSA-2026:19155
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