CVE-2025-69534: Python-Markdown version 3.8 contain a vulnerability where malformed HTML-like sequences can cause html.parser.

Q: How do I fix CVE-2025-69534?

markdown: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2025-69534 being exploited?

CVE-2025-69534 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2025-69534 affect?

CVE-2025-69534 affects markdown. Severity is high (CVSS 7.5). 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, an

Q: How urgent is CVE-2025-69534?

Priority 48/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

HIGH 7.5REMOTEDOWNGRADE

CVE-2025-69534 is a high-severity flaw (CVSS 7.5) affecting markdown. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 rend

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 51%)
CISA exploited list	No
Weakness	CWE-400, CWE-617
Published	2026-03-05
Last modified	2026-09-07

Publisher (CNA): MITRE · Vendor: python-markdown

Last updated 2026-09-07 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-05 15:16 UTCPublished CVE record published
2026-09-07 13:17 UTCUpdated Record last modified

python-markdown markdown DOWNGRADE

Affected: 3.8

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.8

1. Check installed version

pip show markdown

2. No fixed release: DOWNGRADE to a release before 3.8

pip index versions markdown pip install "markdown<3.8"

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Advisories and coverage

Official advisories

AlmaLinux Errata: [ALSA-2026:19366] Important: python-markdown security update 2026-07-07

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-69534?

markdown: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2025-69534 being exploited?

CVE-2025-69534 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-69534 affect?

CVE-2025-69534 affects markdown. Severity is high (CVSS 7.5). 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, an

How urgent is CVE-2025-69534?

Priority 48/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

Python vulnerabilities

Related CVEs

CVE-2026-40890 HIGH 7.5 UPGRADE The package `github.com/gomarkdown/markdown` is a Go library for parsing Markdown text and rendering as HTML

References

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