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8.7 High

CVE-2026-49851 Mistune is a Python Markdown parser with renderers and plugins

Description

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, Mistune is vulnerable to a CPU exhaustion DoS due to superlinear (approximately O(n²)) behavior in parse_link_text. When parsing Markdown containing many consecutive [ characters, parse_link_text repeatedly scans the input using a regex search inside a loop. Each iteration re-scans a large portion of the remaining string, resulting in quadratic-time behavior. An attacker-controlled Markdown input can therefore trigger excessive CPU usage with a very small payload. This vulnerability is fixed in 3.3.0.

Affected products and versions

Product Affected versions Fixed in
mistune 3.3 earliest → < 3.3.0 3.3.0
Red Hat OpenShift AI (RHOAI) Versions not published
Migration Toolkit for Applications 8 Versions not published
Red Hat OpenShift Container Platform 4 Versions not published
Red Hat Satellite 6 Versions not published
Red Hat OpenShift AI 3.4 1787073593 earliest → < 1787073593 1787073593

References

Timeline

  1. Published
  2. Last modified

Other CVEs of mistune

The 28 CVEs of mistune →
CVE-2026-121437 Mistune from 3.3.0 before 3.3.4 contains a denial of service vulnerability that allows remote attackers to exhaust CPU… 8.7 High CVE-2026-121438 Mistune before 3.3.3 contains a denial of service vulnerability in InlineParser.parse_link that allows attackers to… 6.9 Medium CVE-2026-115354 Mistune before 3.3.0 contains a path traversal vulnerability in the opt-in Include directive that allows attackers to… 7.1 High CVE-2026-115355 Mistune before 3.3.0 contains a path traversal vulnerability in the Include directive that allows attackers to read… 8.7 High
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