CVE-2026-115352

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

Published Oct 22, 2026 CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

Sign in to view the affected projects.

Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

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

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Oct 23, 2026, 9:07 PM
Reserved
Oct 22, 2026, 11:20 AM
Status
Deferred
Published
Oct 22, 2026, 7:17 PM
Modified
Oct 23, 2026, 9:17 PM
Severity
Important
Public date
Oct 22, 2026, 7:13 PM