CVE-2025-46656 json
markdownify allows large headline prefixes such as <h9999999>, which causes memory consumption
published 2025-04-26 18 mo ago modified 2026-07-07 4 mo ago also GHSA-7mpr-5m44-h73r , PYSEC-2026-1604 , EUVD-2025-12476
- cvss
- 2.9
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 12%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- pypi markdownify 0.14.1
- python-markdownify python-markdownify 0.14.1
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- partial
- Assessed
- 18 mo ago
Exploit prediction
0.22% chance of exploitation in the next 30 days, higher than 12% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/matthewwithanm/python-markdownify/issues/143 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 2.9 | CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L |
| NVD | 3.1 | 3.3 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L |
| OSV | 3.1 | 2.9 | CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L |
| GitHub | 3.1 | 2.9 | CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | markdownify | <0.14.1 |
0.14.1 |
Affected products
- python-markdownify python-markdownify
Classification
- Weakness
-
- CWE-1284 Improper Validation of Specified Quantity in Input
References
-
github.com
/matthewwithanm/python-markdownify/compare/0.14.0...0.14.1
web, patch
-
github.com
/matthewwithanm/python-markdownify/commit/959561879693bf4a576f99c6733b50b01186aa08
web
-
github.com
/matthewwithanm/python-markdownify/issues/143
exploit, web
-
nvd.nist.gov
/vuln/detail/CVE-2025-46656
advisory
-
github.com
/matthewwithanm/python-markdownify
package
-
pypi.org
/project/markdownify
package
-
github.com
/advisories/GHSA-7mpr-5m44-h73r
advisory
Sources
- CVE List CVE-2025-46656
- GitHub Advisory GHSA-7mpr-5m44-h73r
- NVD CVE-2025-46656
- OSV PYSEC-2026-1604
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.