Incomplete Denylist to Cross-Site Scripting

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 Incomplete Denylist to Cross-Site Scripting via the filterAttributes process. An attack...

CVE-2026-71478

Summary. league/commonmark 1.5.0–2.8.3 is vulnerable due to the AttributesExtension href/src unsafe-link filter bypass when control bytes are embedded in a javascript: URL. The browser may execute the script after the URL is parsed, even with allow_unsafe_links enabled. The issue is caused by ins...

CVE-2026-71478 league/commonmark: AttributesExtension href/src unsafe-link filter bypass via embedded control bytes

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...

CVE-2026-71478 league/commonmark: AttributesExtension href/src unsafe-link filter bypass via embedded control bytes

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...

PT-2026-68813

Name of the Vulnerable Software and Affected Versions league/commonmark versions 0.6.0 through 2.8.3 Description Specially crafted Markdown lines can cause the parser to exhibit quadratic time complexity during conversion. This occurs because several parsing paths repeatedly rescan growing portio...

CVE-2026-57530

Milkdown before 7.21.3 contains a stored cross-site scripting vulnerability in the @milkdown/preset-commonmark and @milkdown/components packages that allows attackers with document write access to execute arbitrary JavaScript in the browser context of any user who opens the document or clicks a...

PT-2026-64409

Name of the Vulnerable Software and Affected Versions Milkdown versions prior to 7.21.3 Description A stored cross-site scripting issue exists in the @milkdown/preset-commonmark and @milkdown/components packages. Attackers with document write access can execute arbitrary JavaScript in the browser...

Ubuntu 20.04 LTS / 22.04 LTS / 24.04 LTS : league/commonmark vulnerabilities (USN-8194-1)

The remote Ubuntu 20.04 LTS / 22.04 LTS / 24.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in the USN-8194-1 advisory. It was discovered that league/commonmark did not properly restrict unsafe attributes when the Attributes extension was enabled. A...

USN-8194-1 php-league-commonmark vulnerabilities

It was discovered that league/commonmark did not properly restrict unsafe attributes when the Attributes extension was enabled. An attacker could possibly use this issue to cause cross-site scripting by injecting malicious code into rendered HTML. This issue only affected Ubuntu 22.04 LTS and...

USN-8194-1: league/commonmark vulnerabilities

It was discovered that league/commonmark did not properly restrict unsafe attributes when the Attributes extension was enabled. An attacker could possibly use this issue to cause cross-site scripting by injecting malicious code into rendered HTML. This issue only affected Ubuntu 22.04 LTS and...

CVE-2026-33347

league/commonmark is a PHP Markdown parser. From version 2.3.0 to before version 2.8.2, the DomainFilteringAdapter in the Embed extension is vulnerable to an allowlist bypass due to a missing hostname boundary assertion in the domain-matching regex. An attacker-controlled domain like...

UBUNTU-CVE-2026-33347

league/commonmark is a PHP Markdown parser. From version 2.3.0 to before version 2.8.2, the DomainFilteringAdapter in the Embed extension is vulnerable to an allowlist bypass due to a missing hostname boundary assertion in the domain-matching regex. An attacker-controlled domain like...

CVE-2026-33347 league/commonmark has an embed extension allowed_domains bypass

league/commonmark is a PHP Markdown parser. From version 2.3.0 to before version 2.8.2, the DomainFilteringAdapter in the Embed extension is vulnerable to an allowlist bypass due to a missing hostname boundary assertion in the domain-matching regex. An attacker-controlled domain like...

CVE-2026-33347

Summary: CVE-2026-33347 affects league/commonmark’s Embed extension DomainFilteringAdapter. A missing hostname boundary assertion in the domain-matching regex allows an attacker-controlled domain (e.g., youtube.com.evil) to bypass the allowlist, potentially treating untrusted content as allowed. ...

CVE-2026-33347

league/commonmark is a PHP Markdown parser. From version 2.3.0 to before version 2.8.2, the DomainFilteringAdapter in the Embed extension is vulnerable to an allowlist bypass due to a missing hostname boundary assertion in the domain-matching regex. An attacker-controlled domain like...

CVE-2026-33347 league/commonmark has an embed extension allowed_domains bypass

league/commonmark is a PHP Markdown parser. From version 2.3.0 to before version 2.8.2, the DomainFilteringAdapter in the Embed extension is vulnerable to an allowlist bypass due to a missing hostname boundary assertion in the domain-matching regex. An attacker-controlled domain like...

CVE-2026-33347 league/commonmark has an embed extension allowed_domains bypass

league/commonmark is a PHP Markdown parser. From version 2.3.0 to before version 2.8.2, the DomainFilteringAdapter in the Embed extension is vulnerable to an allowlist bypass due to a missing hostname boundary assertion in the domain-matching regex. An attacker-controlled domain like...

CVE-2026-33347

league/commonmark is a PHP Markdown parser. From version 2.3.0 to before version 2.8.2, the DomainFilteringAdapter in the Embed extension is vulnerable to an allowlist bypass due to a missing hostname boundary assertion in the domain-matching regex. An attacker-controlled domain like...