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.

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History

Fri, 23 Oct 2026 00:45:00 +0000

Type Values Removed Values Added
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.
Title Mistune before 3.3.0 Quadratic-Time DoS via Unmatched Brackets in Inline Parser
First Time appeared Mistune Project
Mistune Project mistune
Weaknesses CWE-407
CWE-606
CPEs cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*
Vendors & Products Mistune Project
Mistune Project mistune
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 8.7, 'vector': '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'}

threat_severity

Important


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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-10-22T19:13:28.427Z

Reserved: 2026-10-22T11:20:02.626Z

Link: CVE-2026-115352

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Deferred

Published: 2026-10-22T19:17:41.077

Modified: 2026-10-22T19:17:41.187

Link: CVE-2026-115352

cve-icon Redhat

Severity : Important

Publid Date: 2026-10-22T19:13:28Z

Links: CVE-2026-115352 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-10-23T03:45:15Z

Weaknesses