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CVE-2025-69534

7.5 · HIGH

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.

Published Mar 5, 2026CWE-400EPSS 0.59%

Overview

CVE-2025-69534 is a high-severity vulnerability. It was published on March 5, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/Python-Markdown/markdownGitHubgithub.com/Python-Markdown/markdown/actions/runs/15736122892GitHubgithub.com/Python-Markdown/markdown/issues/1534Refwww.openwall.com/lists/oss-security/2026/03/06/4Refaccess.redhat.com/errata/RHSA-2026:10184Refaccess.redhat.com/errata/RHSA-2026:13508Refaccess.redhat.com/errata/RHSA-2026:13512Refaccess.redhat.com/errata/RHSA-2026:13826Refaccess.redhat.com/errata/RHSA-2026:14835Refaccess.redhat.com/errata/RHSA-2026:14873

How CyberStrike helps

Frequently asked questions

What is CVE-2025-69534?

CVE-2025-69534 is a high-severity vulnerability. It was published on March 5, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2025-69534?

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2025-69534?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2025-69534?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-69534 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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