CVE-2026-118694

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.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

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

Configurations

No configuration.

History

28 Oct 2026, 22:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-28 22:17

Updated : 2026-10-29 18:17

NVD link : CVE-2026-118694

Mitre link : CVE-2026-118694

CVE.ORG link : CVE-2026-118694

JSON object : View

Products Affected

No product.

CWE

CWE-407

Inefficient Algorithmic Complexity

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