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Ubuntu 24.04 php-league-commonmark Important XSS Threats USN-8194-1

ubuntu
Calendar Grey April 23, 2026
Dist Ubuntu Esm H88
Security issues fixed in php-league-commonmark for Ubuntu 20.04 to 24.04. Update recommended for safety.
Several security issues were fixed in league/commonmark.

Summary

Several security issues were fixed in league/commonmark.

Software Description:

- php-league-commonmark: Highly-extensible PHP Markdown parser which fully supports the CommonMark and GFM specs

Details:

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 Ubuntu 24.04 LTS. (CVE-2025-46734)

It was discovered that league/commonmark did not properly block certain

disallowed HTML tags in some cases. An attacker could possibly use this

issue to cause cross-site scripting by inserting malicious HTML that

bypassed filtering. (CVE-2026-30838)

It was discovered that league/commonmark did not properly enforce domain

allowlist checks in the Embed extension. An attacker could possibly use

this issue to bypass domain restrictions and cause untrusted conte...

Read the Full Advisory

Topics%20covered

Topics Covered

security advisory cross site scripting Ubuntu important php-league-commonmark commonmark

Update Instructions

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 24.04 LTS
  php-league-commonmark           2.4.2-2ubuntu0.1~esm1
                                  Available with Ubuntu Pro

Ubuntu 22.04 LTS
  php-league-commonmark           1.6.7-1ubuntu0.1~esm1
                                  Available with Ubuntu Pro

Ubuntu 20.04 LTS
  php-league-commonmark           1.3.1-1ubuntu2+esm1
                                  Available with Ubuntu Pro

In general, a standard system update will make all the necessary changes.

References

https://ubuntu.com/security/notices/USN-8194-1

CVE-2025-46734, CVE-2026-30838, CVE-2026-33347

Severity
important
Lowest
Low
Medium
High
Critical

Ubuntu Security Notice USN-8194-1

Topics%20covered

Topics Covered

security advisory cross site scripting Ubuntu important php-league-commonmark commonmark

Package Information

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