CVE-2026-118694

HIGH 7.5

python-markdown2 through 2.5.5 Denial of Service via Unclosed Inline Link Destinations

CVSS Score

7.5

EPSS Score

0.0%

EPSS Percentile

0th

python-markdown2 through 2.5.5 contains a denial of service vulnerability that allows remote users to exhaust CPU by submitting Markdown with unclosed inline link destinations. Attackers can submit repeated '[a](' or '![a](' sequences, causing _find_balanced to rescan the remaining document for each link and consume quadratic CPU time.

CWE	CWE-407
Vendor	trentm
Product	python-markdown2
Published	Oct 28, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Affected Versions

trentm / python-markdown2

0 ≤ 2.5.5

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/trentm/python-markdown2/issues/750 github.com: https://github.com/trentm/python-markdown2 github.com: https://github.com/trentm/python-markdown2/blob/2.5.5/lib/markdown2.py#L1478-L1492 github.com: https://github.com/trentm/python-markdown2/blob/2.5.5/lib/markdown2.py#L3029 github.com: https://github.com/trentm/python-markdown2/pull/751 vulncheck.com: https://www.vulncheck.com/advisories/python-markdown2-through-2.5.5-denial-of-service-via-unclosed-inline-link-destinations

Credits

Muhammadyusuf Dilmurodov (agrresore) ParamTanna