CVE-2026-115349 Details
Description
Mistune from 3.0.0 before 3.3.0 contains an algorithmic complexity denial of service vulnerability in the parse_link_text function in src/mistune/helpers.py. Attackers can submit markdown with deeply nested square brackets triggering quadratic parsing time, exhausting server CPU with small crafted requests.
A denial-of-service vulnerability has been identified in Mistune versions 3.0.0 prior to 3.3.0. The issue arises in the 'parse_link_text' function within 'src/mistune/helpers.py', where the handling of deeply nested square brackets in markdown links creates an algorithmic complexity problem. This flaw allows attackers to submit crafted markdown that triggers quadratic parsing times, leading to significant CPU exhaustion on the server with relatively small requests.
Users are advised to update to Mistune version 3.3.0 or later, where this vulnerability has been patched.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Oct 22, 2026CISA-ADP
Assessed Oct 26, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/lepture/mistune/security/advisories/GHSA-3q64-rw38-243v | [email protected] | AdvisoryExploitTechnical DescriptionVendor |
| https://www.vulncheck.com/advisories/mistune-3.0.0-before-3.3.0-denial-of-service-via-nested-bracket-parsing | [email protected] | Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-1333 | Inefficient Regular Expression Complexity | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Mistune | >= 3.0.0, <= 3.2.1 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Oct 26, 2026 | CVE Modified | CISA-ADP |
| Oct 22, 2026 | New CVE Received | [email protected] |