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CVE-2025-46656

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

2.9 LowFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
High
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
Low

Exploit likelihood

0.22%Up 0.2 points since Apr 27, 2025
90%50%10%1%

What each source reports

CVE List Score used 2.9

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.

Record
CVE-2025-46656
CVSS 3.1
2.9 LowCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness
CWE-1284
Updated
2026-11-02
EUVDEUVD-2025-12476 2.9

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.

Record
EUVD-2025-12476
CVSS 3.1
2.9 LowCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Updated
2026-11-02
GitHub AdvisoriesGHSA-7mpr-5m44-h73r 2.9

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

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.

Record
GHSA-7mpr-5m44-h73r
CVSS 3.1
2.9 LowCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness
CWE-1284
Updated
2026-11-02
NVD 2.9

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.

Record
CVE-2025-46656
CVSS 3.1
2.9 LowCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
CVSS 3.1
3.3 LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Weakness
CWE-1284
Updated
2026-11-02
OSV 2.9

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.

Record
CVE-2025-46656
CVSS 3.1
2.9 LowCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness
CWE-1284
Updated
2026-11-02
OSVGHSA-7mpr-5m44-h73r 2.9

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

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.

Record
GHSA-7mpr-5m44-h73r
CVSS 3.1
2.9 LowCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness
CWE-1284
Updated
2026-11-02
OSVPYSEC-2026-1604 2.9

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

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.

Record
PYSEC-2026-1604
CVSS 3.1
2.9 LowCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
markdownify
PyPI
 before 0.14.1
0.14.1
markdownify
PyPI
 before 0.14.1, plus listed versions
0.10.00.10.10.10.20.10.30.11.0
Show 33 moreShow less
0.11.10.11.20.11.40.11.50.11.60.12.10.13.00.13.10.14.00.2.00.3.00.4.00.4.10.5.10.5.20.5.30.6.00.6.10.6.30.6.40.6.50.6.60.7.00.7.10.7.20.7.30.7.40.8.00.8.10.9.00.9.20.9.30.9.4
0.14.1

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2025-46656 is a low vulnerability (CVSS 2.9) in Matthewwithanm Markdownify, published April 26, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.22%, the 12th percentile. Fixed in markdownify 0.14.1.

References

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