CVE-2026-59922: CWE-407: Inefficient Algorithmic Complexity in lepture mistune
CVE-2026-59922 is a high-severity vulnerability in the lepture mistune Python Markdown parser prior to version 3.3.0. The issue involves inefficient algorithmic complexity in the handling of certain marker pairs (tilde, equals-sign, caret) used by strikethrough, mark, or insert plugins. This inefficiency causes quadratic processing time when scanning for matching markers, leading to potential denial of service through CPU exhaustion. The vulnerability is fixed in version 3.3.0.
AI Analysis
Technical Summary
Mistune versions before 3.3.0 contain an inefficient algorithmic complexity issue 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 time complexity. This can be exploited to cause denial of service by exhausting CPU resources. The problem is resolved in mistune version 3.3.0.
Potential Impact
An attacker can cause a denial of service condition by triggering excessive CPU usage due to the quadratic complexity in marker scanning. There is no impact on confidentiality or integrity, but availability is affected.
Mitigation Recommendations
Upgrade mistune to version 3.3.0 or later, where this vulnerability is fixed. No other mitigation or temporary workaround is documented.
CVE-2026-59922: CWE-407: Inefficient Algorithmic Complexity in lepture mistune
Description
CVE-2026-59922 is a high-severity vulnerability in the lepture mistune Python Markdown parser prior to version 3.3.0. The issue involves inefficient algorithmic complexity in the handling of certain marker pairs (tilde, equals-sign, caret) used by strikethrough, mark, or insert plugins. This inefficiency causes quadratic processing time when scanning for matching markers, leading to potential denial of service through CPU exhaustion. The vulnerability is fixed in version 3.3.0.
CVSS v3.1
Score 7.5high
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Mistune versions before 3.3.0 contain an inefficient algorithmic complexity issue 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 time complexity. This can be exploited to cause denial of service by exhausting CPU resources. The problem is resolved in mistune version 3.3.0.
Potential Impact
An attacker can cause a denial of service condition by triggering excessive CPU usage due to the quadratic complexity in marker scanning. There is no impact on confidentiality or integrity, but availability is affected.
Mitigation Recommendations
Upgrade mistune to version 3.3.0 or later, where this vulnerability is fixed. No other mitigation or temporary workaround is documented.
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: 07/08/2026, 16:43:22 UTC
Last updated: 07/08/2026, 16:48:14 UTC
Views: 3
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