CVE-2026-59927 Mistune directives/include: mutual `.. include::` recursion crashes the renderer with `RecursionError`, denial of service via two attacker-controlled markdown files

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...

CVE-2026-59927 Mistune directives/include: mutual `.. include::` recursion crashes the renderer with `RecursionError`, denial of service via two attacker-controlled markdown files

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...

CVE-2026-59927

The CVE-2026-59927 issue affects Mistune, a Python Markdown parser. Before version 3.3.0, the Include directive in src/mistune/directives/include.py only detected direct self-includes and failed to handle indirect cycles, enabling two Markdown files that include each other to cause unbounded recu...

CVE-2026-59928 Mistune block_parser: quadratic-time parsing on long lists of repeated reference-link definitions

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a Markdown document containing many repeated or distinct reference-link definitions causes quadratic work in src/mistune/blockparser.py and the reflinks environment dictionary handling, allowing denial of service...

CVE-2026-59928

Mistune (Python Markdown parser) prior to version 3.3.0 is vulnerable to a denial of service due to quadratic work in the block_parser.py processing of long references and in the ref_links environment dictionary. The issue arises when a Markdown document contains many repeated or distinct referen...

CVE-2026-59924

Mistune (Python Markdown parser) prior to v3.3.0 contains a path traversal flaw in Include.parse() where include paths are joined/normalized without ensuring the result stays inside the markdown directory. When processing markdown files via md.read(), crafted include paths could read files outsid...

CVE-2026-59924 Mistune: Arbitrary File Read via Include directive path traversal

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, Include.parse joins and normalizes user-supplied include paths without verifying that the result remains within the intended markdown directory, allowing crafted include paths to access files outside that directory wh...

CVE-2026-59924

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, Include.parse joins and normalizes user-supplied include paths without verifying that the result remains within the intended markdown directory, allowing crafted include paths to access files outside that directory wh...

CVE-2026-59929 Mistune renderers/html.safe_url: HARMFUL_PROTOCOLS list misses legacy and chained schemes that historically chain to `javascript:` execution

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the safeurl filter in src/mistune/renderers/html.py blocks only javascript:, vbscript:, file:, and data: schemes, allowing legacy or chained schemes such as feed:, view-source:, jar:, livescript:, mocha:, ms-its:, mk:...

CVE-2026-59925 inline_parser: quadratic-time parsing on long runs of `**x**` and `***x***` emphasis pairs

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, long sequences of well-formed double-asterisk or triple-asterisk emphasis pairs around a character cause quadratic work in src/mistune/inlineparser.py because the parser scans forward for matching close markers from...

CVE-2026-59925

The CVE-2026-59925 affects Mistune, a Python Markdown parser. Before version 3.3.0, long sequences of well-formed emphasis markers (/x / or /x * around a character) trigger quadratic work in src/mistune/inline_parser.py by scanning for matching close markers from each opening run, enabling denial...

CVE-2026-59923

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, HTMLRenderer.safeurl does not block percent-encoded javascript URIs, allowing attacker-supplied Markdown links or images to bypass URL protections and execute script in rendered HTML. This issue is fixed in version...

CVE-2026-59930 Mistune toc / TableOfContents directive: heading IDs use predictable `toc_N` numbering with no slugification, allowing collision with attacker-controlled `id="toc_N"` content

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the toc plugin and TableOfContents directive generate heading IDs as predictable tocN values without slugifying the heading text, allowing attacker-controlled id="tocN" content to collide with generated anchors and...

CVE-2026-59930 Mistune toc / TableOfContents directive: heading IDs use predictable `toc_N` numbering with no slugification, allowing collision with attacker-controlled `id="toc_N"` content

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the toc plugin and TableOfContents directive generate heading IDs as predictable tocN values without slugifying the heading text, allowing attacker-controlled id="tocN" content to collide with generated anchors and...

CVE-2026-59930

Mistune (Python Markdown parser) prior to 3.3.0 has a vulnerability in the toc/TableOfContents directive: heading IDs are generated as predictable toc_N values without slugifying the heading text. This can allow attacker-controlled id="toc_N" content to collide with generated anchors, potentially...

CVE-2026-59922

Mistune (Python Markdown parser) contains a quadratic-time DoS in formatting.py for long runs of marker pairs (x , ==x==, ^^x^^) in the strikethrough/mark/insert plugins. The issue arises from scanning for matching markers from every possible start position, causing CPU exhaustion. It is fixed in...

CVE-2026-59922

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 ea...

CVE-2026-59922 Mistune plugins/formatting: quadratic-time parsing on long runs of `~~x~~`, `==x==`, and `^^x^^` markers (strikethrough / mark / insert)

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 ea...

PT-2026-56508

Name of the Vulnerable Software and Affected Versions Mistune versions prior to 3.3.0 Description A flaw in the Python Markdown parser occurs when the strikethrough, mark, or insert plugins scan for matching markers from each possible start position. Specifically, a sequence of closed tilde,...

PT-2026-56517

Name of the Vulnerable Software and Affected Versions Mistune versions prior to 3.3.0 Description Mistune is a Python Markdown parser with renderers and plugins. The Include.parse function joins and normalizes user-supplied include paths without verifying that the result remains within the intend...