CVE-2025-69534

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.

Database specific

{
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/69xxx/CVE-2025-69534.json",
    "cna_assigner": "mitre"
}

References

Affected packages

Git / github.com/python-markdown/markdown

Affected ranges

Type

GIT

Repo

https://github.com/python-markdown/markdown

Events

Introduced

b34e1d03387be771aa626241fe56f8f0c34243f2

Last affected

b34e1d03387be771aa626241fe56f8f0c34243f2

Database specific

{
    "source": "CPE_STRING",
    "cpe": "cpe:2.3:a:python-markdown:markdown:3.8:*:*:*:*:python:*:*",
    "extracted_events": [
        {
            "introduced": "3.8"
        },
        {
            "last_affected": "3.8"
        }
    ]
}

Affected versions

3.*

3.8

Database specific

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-69534.json"