CVE-2026-115352

Mistune before 3.3.0 Quadratic-Time DoS via Unmatched Brackets in Inline Parser

State: Published
Severity: 8.7 High
Published: Oct 22, 2026
Updated: Oct 23, 2026
Reserved: Oct 22, 2026

Description

Mistune before 3.3.0 contains an algorithmic complexity vulnerability in the inline link parser that allows unauthenticated attackers to exhaust CPU by submitting long runs of unmatched '[' characters. Attackers can send small markdown payloads that trigger O(N^2) parse_link_text and parse_link_label probing, occupying rendering workers for 30+ seconds per 16 KB input.

Scores

CVSS	Score	Vector	Source
4.0	8.7 High	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N	VulnCheck
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	VulnCheck

Weaknesses

CWE-407 Inefficient Algorithmic Complexity

Affected Products

Product	Versions
mistunelepture	before 3.3.0Affected 3.3.0Not affected

References

GitHub Security Advisory (GHSA-xrpv-r66x-8p7j)vendor-advisory
VulnCheck Advisory: Mistune before 3.3.0 Quadratic-Time DoS via Unmatched Brackets in Inline Parserthird-party-advisory

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