CVE-2026-86429

CVE-2026-86429 affects the thephpleague/commonmark PHP library (versions ≥ 1.5.0,

PT-2026-86796

league/commonmark versions before 2.9.1 contain multiple denial of service vulnerabilities in fenced code block detection, reference link label lookup, and emphasis delimiter processing that perform super-linear work on crafted input. Attackers can submit specially crafted Markdown with long...

Linux Distros Unpatched Vulnerability : CVE-2026-86431

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - league/commonmark thephpleague/commonmark versions = 2.7.0 and 2.9.1 contain a cross-site scripting vulnerability in the AttributesExtension. Prefixing an...

PT-2026-86800

league/commonmark versions = 2.0.0 and 2.8.4 patched in 2.9.0 contain a denial of service vulnerability in UniqueSlugNormalizer::normalize, which restarts its numeric-suffix search from 1 on every slug collision, resulting in OK^2 time complexity for K headings that collapse to the same base slug...

PT-2026-86797

league/commonmark thephpleague/commonmark versions = 2.7.0 and 2.9.1 contain a cross-site scripting vulnerability in the AttributesExtension. Prefixing an attribute name with a single U+000C form feed byte e.g. x0Conclick="alert1" bypasses the AttributesHelper::filterAttributes 'on' event-handler...

Linux Distros Unpatched Vulnerability : CVE-2026-86430

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - league/commonmark versions before 2.9.1 contain multiple denial of service vulnerabilities in fenced code block detection, reference link label lookup, and...

Linux Distros Unpatched Vulnerability : CVE-2026-86434

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - league/commonmark versions = 2.0.0 and 2.8.4 patched in 2.9.0 contain a denial of service vulnerability in UniqueSlugNormalizer::normalize, which restarts its...

PT-2026-86795

The league/commonmark thephpleague/commonmark library in versions = 1.5.0 and 2.9.1 contains quadratic parsing complexity in its SmartPunctExtension and AttributesExtension. When either extension is explicitly registered on the Environment they are not enabled by default and are excluded from the...

GHSA-8RR7-CVQ3-GMFH league/commonmark: Denial of service via distinctly-named attributes in the Attributes extension

Impact AttributesExtension ships with the library but must be explicitly registered on the Environment; it is not included in CommonMarkConverter, GithubFlavoredMarkdownConverter, or GithubFlavoredMarkdownExtension. Applications that do not register AttributesExtension are not affected by this...

GHSA-JJV6-8J6V-6J52 league/commonmark: Denial of service in the SmartPunct and Attributes extensions

Impact Two first-party extensions contain quadratic parsing paths. Both ship with the library but must be explicitly registered on the Environment; neither is included in CommonMarkConverter, GithubFlavoredMarkdownConverter, or GithubFlavoredMarkdownExtension. Applications that do not register...

GHSA-F8FG-PG57-V4J8 league/commonmark XSS: `on*` event-handler filter in `AttributesExtension` bypassed with a U+000C form feed

Summary The AttributesExtension documents a security guarantee: Note: Attributes starting with on e.g. onclick or onerror are capable of executing JavaScript code and are therefore never allowed by default. You must explicitly add them to the allow list if you want to use them. —...

GHSA-J8PM-GJ4C-RQ4X league/commonmark: Denial of service via crafted code fences, reference links, and emphasis delimiters

Impact Affected versions of league/commonmark perform super-linear work on three independent parsing paths, all of which are reachable on a stock new CommonMarkConverter with default configuration and no extensions registered. Each trigger fits on a single line of input, so no complex Markdown...

Linux Distros Unpatched Vulnerability : CVE-2026-71488

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 0.6.0 until 2.9.0, specially crafted Markdown lines can cause the parser ...

DEBIAN-CVE-2026-71488

league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 0.6.0 until 2.9.0, specially crafted Markdown lines can cause the parser to have quadratic time complexity when converting, because several parsing paths repeatedly rescan growing portions of a line to translat...

DEBIAN-CVE-2026-71478

league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 1.5.0 until 2.9.0, the AttributesExtension's href and src unsafe-link filter can be bypassed by embedding control bytes, such as a tab, carriage return, line feed, or leading C0 control character, in a...

CVE-2026-71478

league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 1.5.0 until 2.9.0, the AttributesExtension's href and src unsafe-link filter can be bypassed by embedding control bytes, such as a tab, carriage return, line feed, or leading C0 control character, in a...

UBUNTU-CVE-2026-71478

league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 1.5.0 until 2.9.0, the AttributesExtension's href and src unsafe-link filter can be bypassed by embedding control bytes, such as a tab, carriage return, line feed, or leading C0 control character, in a...

Inefficient Algorithmic Complexity

Overview league/commonmark is a PHP-based Markdown parser which supports the full CommonMark spec. It is based on the CommonMark JS reference implementation. Affected versions of this package are vulnerable to Inefficient Algorithmic Complexity via the FootnoteExtension process. An attacker can...

league/commonmark: Quadratic-time denial of service when parsing crafted Markdown

Impact Affected versions of league/commonmark can have quadratic time complexity when parsing specially crafted Markdown lines. In practical terms, doubling the length of an affected line can make the parser perform roughly four times as much work. The parser identifies locations using character...

GHSA-2Q4P-G7HV-5RGV league/commonmark: Quadratic-time denial of service when parsing crafted Markdown

Impact Affected versions of league/commonmark can have quadratic time complexity when parsing specially crafted Markdown lines. In practical terms, doubling the length of an affected line can make the parser perform roughly four times as much work. The parser identifies locations using character...