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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
SUSE Affected 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Affected | — |
Debian Mixed 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Fixed | 3.13.4-1 |
| sid | Fixed | 3.13.4-1 |
| forky | Fixed | 3.13.4-1 |
| bullseye | Affected | — |
| bookworm | Affected | — |
Red Hat Fixed 1 release
| Version | Status | Fixed in |
|---|---|---|
| 9 | Fixed | — |
References
- https://nvd.nist.gov/vuln/detail/CVE-2025-69534
- https://github.com/Python-Markdown/markdown/issues/1534
- https://github.com/Python-Markdown/markdown/pull/1535
- https://github.com/Python-Markdown/markdown
- https://github.com/Python-Markdown/markdown/actions/runs/15736122892
- http://www.openwall.com/lists/oss-security/2026/03/06/4
- https://access.redhat.com/errata/RHSA-2026:19366
- https://www.suse.com/security/cve/CVE-2025-69534.html
- https://security-tracker.debian.org/tracker/CVE-2025-69534
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.