Mistune: Potential DoS via quadratic-time parsing in parse_link_text

SummaryMistune is vulnerable to a CPU exhaustion DoS due to superlinear approximately On² behavior in parselinktext. A relatively small input consisting of repeated characters causes significant parsing slowdown. Affected componentmistune/inlineparser.py → parselinktext DescriptionWhen parsing...

PYSEC-2026-2651 Mistune has a ReDoS in LINK_TITLE_RE that allows denial of service via crafted Markdown input

Summary A ReDoS Regular Expression Denial of Service vulnerability in LINKTITLERE allows an attacker who can supply Markdown for parsing to cause denial of service. A crafted 58-byte Markdown document blocks the parser for approximately 6 seconds measured on Apple M2, Python 3.14.3, with...

CVE-2026-59929

A flaw was found in Mistune, a Python Markdown parser. The safeurl filter, intended to prevent malicious Uniform Resource Locators URLs, did not adequately block all potentially harmful schemes. This oversight allows an attacker to embed specially crafted URLs using legacy or chained schemes with...

CVE-2026-59923

A flaw was found in Mistune, a Python Markdown parser. This vulnerability allows an attacker to bypass URL protections by using specially crafted Markdown links or images containing percent-encoded javascript URIs. This can lead to the execution of arbitrary scripts in the rendered HTML,...

CVE-2026-59928

A flaw was found in Mistune, a Python Markdown parser. A remote attacker could exploit this vulnerability by providing a specially crafted Markdown document containing numerous repeated or distinct reference-link definitions. This can lead to excessive processing, causing CPU exhaustion and a...

Linux Distros Unpatched Vulnerability : CVE-2026-59924

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - 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...

Linux Distros Unpatched Vulnerability : CVE-2026-59923

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - 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...

Linux Distros Unpatched Vulnerability : CVE-2026-59928

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - 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...

Linux Distros Unpatched Vulnerability : CVE-2026-59922

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - 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...

Inefficient Algorithmic Complexity

Overview Affected versions of this package are vulnerable to Inefficient Algorithmic Complexity in the inlineparser process. An attacker can cause excessive resource consumption by submitting input containing long sequences of double-asterisk or triple-asterisk emphasis pairs, leading to...

DEBIAN-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-2026-59923

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-2026-59928 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-2026-59929 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

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-2026-59926

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, renderadmonition in src/mistune/directives/admonition.py concatenates the Admonition directive :class: option into the HTML class attribute without escaping, allowing attribute injection and cross-site scripting even...

Linux Distros Unpatched Vulnerability : CVE-2026-49851

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - 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...

Linux Distros Unpatched Vulnerability : CVE-2026-44896

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - Mistune is a Python Markdown parser with renderers and plugins. In 3.2.0 and earlier, in src/mistune/directives/image.py, the renderfigure function concatenates...

Linux Distros Unpatched Vulnerability : CVE-2026-44897

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, HTMLRenderer.heading builds the opening tag by string-concatenating the id...

Linux Distros Unpatched Vulnerability : CVE-2026-44899

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, the Image directive plugin validates the :width: and :height: options with a reg...