CVE-2025-69534Disclosure(python-markdown / markdown)

LOWCVSS 7.5 · HIGH

Signal is active with 4 mentions in latest observed window

Immediate actions

Patch python-markdown markdown systems immediately

Recommended action window: Monitor and triage in normal cycle

NVD 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.

python-markdown CVEs Back to dashboard

0.5/ 10 priority

Sources & remediation

Exploit / PoC references

https://github.com/Python-Markdown/markdown/issues/1534

Vendor / third-party advisories

http://www.openwall.com/lists/oss-security/2026/03/06/4

Other references

Weakness type (CWE)

CWE-400CWE-617

Priority

LOW

Exploitation

NONE

PoC

YES

Patch

AVAILABLE

Momentum

STABLE

Are you affected?

If you run products in this scope, you should treat this CVE as relevant to your environment.

markdown

Threat summary

Patch or workaround signal is available
7 mentions across 3 observed days
Momentum state: stable

What's happening

Patch or workaround mentioned in 3 signals
Technical details provided in 5 signals
Disclosure: 4 classified signals
Peaked at 4 mentions on most recent observed day (2026-03-09)
7 total mentions across 3 days

Affected systems

Vendors

python-markdown

Products

markdown

1 version affected across 1 product

Deep dive

Activity timeline7 mentions / 3d

Signal classification2 categories

Disclosure

457.1%

Patch

342.9%

Referenced assets7 URLs

By indicator

Classification over time

Date	Total	Labels

2026-03-05	1	Disclosure1
2026-03-08	2	Disclosure2
2026-03-09	4	Disclosure1Patch3

Full discourse7 posts

Open Source Security mailing list@oss_security215d
Disclosure
CVE-2025-69534: Python-Markdown: Malformed HTML-like sequences can cause html.parser.HTMLParser to raise an unhandled AssertionError during Markdown parsing https://www.openwall.com/lists/oss-security/2026/03/06/4 remote DoS in any application parsing untrusted Markdown, and can lead to Information Disclosure
Post summary
CVE-2025-69534 involves a flaw in Python‑Markdown’s HTML parser that can cause unhandled assertion errors, leading to denial of service and information disclosure when processing untrusted Markdown. No exploitation evidence, patch, or PoC is referenced.
00030376
4.4K followersView on X
Ferramentas Linux@Cezar_H_Linux215d
Patch
Critical DoS vulnerability patched in openSUSE 15.6 (CVE-2025-69534). The flaw in python-Markdown lets remote attackers crash apps via incomplete HTML markup. Read more: 👉 https://tinyurl.com/53beckja #openSUSE #Security https://t.co/CPWGl76yoy
Post summary
The tweet announces that CVE‑2025‑69534, a critical DoS vulnerability in python‑Markdown that crashes apps via incomplete HTML markup, has been patched in openSUSE 15.6.
0001080
1.3K followersView on X
CVE@CVEnew215d
Disclosure
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 M… https://www.cve.org/CVERecord?id=CVE-2025-69534
Post summary
The text announces a vulnerability in Python-Markdown 3.8 that triggers an unhandled AssertionError when parsing malformed HTML-like content, with no PoC, exploit, or patch details provided.
00010274
56.6K followersView on X
ThreatCluster@threatcluster215d
Patch
openSUSE Leap 15.6 patches critical python-Markdown bug (CVE-2025-69534) that can crash apps parsing untrusted Markdown. Users should update immediately via YaST online_update or zypper patch. https://threatcluster.io/cluster/critical-crash-risk-in-opensuse-leap-156-due-to-python-markd-e686ec80
Post summary
The post announces a critical patch for CVE-2025-69534 in openSUSE Leap 15.6 and urges users to update via YaST or zypper, with no evidence of active exploitation or detailed technical information.
0000068
100 followersView on X
Ferramentas Linux@Cezar_H_Linux215d
Patch
Heads-up, #openSUSE community! A new security patch for Leap 15.6 is out, addressing CVE-2025-69534 in python-Markdown Read more: Read more: 👉 https://tinyurl.com/3cwkrbhf #Security https://t.co/SJnbVRc89E
Post summary
The tweet announces a new patch for openSUSE Leap 15.6 that addresses CVE‑2025‑69534, without providing exploitation details or vulnerability specifics.
0000062
1.3K followersView on X
Infoflowcloud@infoflowcloud215d
Disclosure
🚨*CVE* 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 M… https://www.cve.org/CVERecord?id=CVE-2025-69534 ----- Traducción: CVE-2025-69534 Pyt… http://infoflow.cloud`
Post summary
The tweet reports CVE‑2025‑69534, a flaw in Python‑Markdown 3.8 that triggers an unhandled AssertionError when parsing malformed HTML‑like input, offering technical details but no PoC, exploit, patch, or evidence of active exploitation.
0000086
56 followersView on X
Vulmon Vulnerability Feed@VulmonFeeds219d
Disclosure
CVE-2025-69534 Unauthenticated Denial of Service in Python-Markdown 3.8 via HTML Parsing Exception https://vulmon.com/vulnerabilitydetails?qid=CVE-2025-69534
Post summary
The text announces CVE‑2025‑69534 as an unauthenticated denial‑of‑service vulnerability in Python‑Markdown 3.8, providing basic technical details but no PoC, exploit code, or patch information.
0000050
4.0K followersView on X

CPE platform detail1 entries

Part:

Vendor:

Product:

Version:

Target SW:

Target HW:

1 of 1 entries

Part	Vendor	Product	Version	Target SW	Target HW
App	python-markdown	markdown	3.8	python	-

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What researchers are saying

CVE-2025-69534

ThreatCluster[verified]@threatclusterPatch

The post announces a critical patch for CVE-2025-69534 in openSUSE Leap 15.6 and urges users to update via YaST or zypper, with no evidence of active exploitation or detailed technical information.

Open Source Security mailing list@oss_securityDisclosure

CVE-2025-69534 involves a flaw in Python‑Markdown’s HTML parser that can cause unhandled assertion errors, leading to denial of service and information disclosure when processing untrusted Markdown. No exploitation evidence, patch, or PoC is referenced.

Ferramentas Linux@Cezar_H_LinuxPatch

The tweet announces that CVE‑2025‑69534, a critical DoS vulnerability in python‑Markdown that crashes apps via incomplete HTML markup, has been patched in openSUSE 15.6.

CVE@CVEnewDisclosure

The text announces a vulnerability in Python-Markdown 3.8 that triggers an unhandled AssertionError when parsing malformed HTML-like content, with no PoC, exploit, or patch details provided.

Ferramentas Linux@Cezar_H_LinuxPatch

The tweet announces a new patch for openSUSE Leap 15.6 that addresses CVE‑2025‑69534, without providing exploitation details or vulnerability specifics.

Infoflowcloud@infoflowcloudDisclosure

The tweet reports CVE‑2025‑69534, a flaw in Python‑Markdown 3.8 that triggers an unhandled AssertionError when parsing malformed HTML‑like input, offering technical details but no PoC, exploit, patch, or evidence of active exploitation.

Vulmon Vulnerability Feed@VulmonFeedsDisclosure

The text announces CVE‑2025‑69534 as an unauthenticated denial‑of‑service vulnerability in Python‑Markdown 3.8, providing basic technical details but no PoC, exploit code, or patch information.