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Not in CISA KEV
LOW severity

CVE-2025-46656 — markdownify

LOWFix: matthewwithanm/python-markdownify@9595618

CVE-2025-46656 is a low-severity (CVSS 2.9) CWE-1284 vulnerability in markdownify. A fix is available for markdownify — see the affected versions and patch details below.

markdownify allows large headline prefixes such as <h9999999>, which causes memory consumption

Also known asGHSA-7mpr-5m44-h73rPYSEC-2026-1604
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for CVE-2025-46656.

EPSS Exploitation Probability

via FIRST.org ↗
0.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs13th percentile — riskier than 13% of all scored CVEsHighest risk
0.00%0.24%0.48%0.72%0.1%0.2%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐍markdownify

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

python-markdownify (aka markdownify) before 0.14.1 allows large headline prefixes such as <h9999999> in addition to <h1> through <h6>. This causes memory consumption.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPImarkdownifyall versions0.14.1pip install --upgrade 'markdownify==0.14.1'

Affected Products

1 product · 1 configurations
Application
markdownifymatthewwithanm
< 0.14.1
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for markdownify, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update markdownify to 0.14.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-46656 is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

python-markdownify (aka markdownify) before 0.14.1 allows large headline prefixes such as <h9999999> in addition to <h1> through <h6>. This causes memory consumption.
O3 Security · Impact-Aware SCA

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CVE-2025-46656: markdownify — Fixed in 0.14.1