CVE-2026-121437
HIGH
MEDIUM
Priority: 0.05
BB Relevance:
78/100
Published: 2026-11-03
Modified: 2026-11-03
First seen: 2026-11-03
Status: active
Attack Surface
Network
Low Complexity
No Auth
No Interaction
CVSS Vector Breakdown
AV:
Network
AC:
Low
PR:
None
UI:
None
AT:
None
VC:
None
VI:
None
VA:
High
Description
Mistune from 3.3.0 before 3.3.4 contains a denial of service vulnerability that allows remote attackers to exhaust CPU through quadratic-time emphasis delimiter processing. Attackers can submit small markdown documents with repeated patterns like "*a_b" to trigger an O(n²) index-fixup loop, stalling workers for seconds.
Weakness Classification (1)
Affected Software (2)
References & Advisories (3)
vendor-advisory
third-party-advisory
patch