CVE-2026-59927: medium-severity vulnerability in lepture mistune
Mistune directives/include: mutual `.. include::` recursion crashes the renderer with `RecursionError`, denial of service via two attacker-controlled markdown files
Published
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13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.3epss 0.5%
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the Include directive in src/mistune/directives/include.py detects only direct self-includes and not indirect cycles, allowing two markdown files that include each other to trigger unbounded recursion, raise RecursionError, and crash the rendering request. This issue is fixed in version 3.3.0.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Affected products
lepture · mistuneRelated CVEs — lepture mistune
In the same product, most dangerous first.
CVE-2026-59928HIGHMistune block_parser: quadratic-time parsing on long lists of repeated reference-link definitionsEPSS 0.7%CVE-2026-59925HIGHinline_parser: quadratic-time parsing on long runs of `**x**` and `***x***` emphasis pairsEPSS 0.6%CVE-2026-59922HIGHMistune plugins/formatting: quadratic-time parsing on long runs of `~~x~~`, `==x==`, and `^^x^^` markers (strikethrough / mark / insert)EPSS 0.6%CVE-2026-121437HIGHMistune 3.3.0 before 3.3.4 Quadratic-Time DoS via _process_emphasis_delimitersEPSS 0.6%CVE-2026-33079HIGHMistune ReDoS in LINK_TITLE_RE allows denial of service with crafted Markdown titlesEPSS 0.6%CVE-2026-49851HIGHMistune: Potential DoS via quadratic-time parsing in parse_link_textEPSS 0.5%