CVE-2026-59922: CWE-407: Inefficient Algorithmic Complexity in lepture mistune
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or caret marker pairs around a character causes quadratic work in src/mistune/plugins/formatting.py when the strikethrough, mark, or insert plugin scans for matching markers from each possible start position, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.
AI Analysis
Technical Summary
Mistune versions before 3.3.0 contain an inefficient algorithmic complexity vulnerability (CWE-407) in src/mistune/plugins/formatting.py. When processing runs of closed tilde (~), equals-sign (=), or caret (^) marker pairs around a character, the strikethrough, mark, or insert plugins scan for matching markers from each possible start position, resulting in quadratic computational work. This inefficiency can be exploited to cause denial of service by exhausting CPU resources. The issue is resolved in version 3.3.0.
Potential Impact
The vulnerability allows an attacker to cause denial of service by triggering excessive CPU consumption during Markdown parsing, impacting availability. There is no impact on confidentiality or integrity. No known exploits are reported in the wild.
Mitigation Recommendations
Upgrade Mistune to version 3.3.0 or later, where this vulnerability is fixed. Patch status is confirmed by the vendor advisory indicating the fix in 3.3.0.
CVE-2026-59922: CWE-407: Inefficient Algorithmic Complexity in lepture mistune
Description
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or caret marker pairs around a character causes quadratic work in src/mistune/plugins/formatting.py when the strikethrough, mark, or insert plugin scans for matching markers from each possible start position, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.
CVSS v3.1
Score 7.5high
Affected software
Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Mistune versions before 3.3.0 contain an inefficient algorithmic complexity vulnerability (CWE-407) in src/mistune/plugins/formatting.py. When processing runs of closed tilde (~), equals-sign (=), or caret (^) marker pairs around a character, the strikethrough, mark, or insert plugins scan for matching markers from each possible start position, resulting in quadratic computational work. This inefficiency can be exploited to cause denial of service by exhausting CPU resources. The issue is resolved in version 3.3.0.
Potential Impact
The vulnerability allows an attacker to cause denial of service by triggering excessive CPU consumption during Markdown parsing, impacting availability. There is no impact on confidentiality or integrity. No known exploits are reported in the wild.
Mitigation Recommendations
Upgrade Mistune to version 3.3.0 or later, where this vulnerability is fixed. Patch status is confirmed by the vendor advisory indicating the fix in 3.3.0.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-07-07T18:20:06.125Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a4e7ad5c9d9e3dbe36a7de9
Added to database: 07/08/2026, 16:29:09 UTC
Last enriched: 07/16/2026, 10:07:08 UTC
Last updated: 08/22/2026, 10:52:10 UTC
Views: 70
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.