CVE-2026-33347

Publication date 24 March 2026

Last updated 10 July 2026

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

6.1 · Medium

Score breakdown

Description

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 youtube.com.evil passes the allowlist check when youtube.com is an allowed domain. This issue has been patched in version 2.8.2.

Status

Package Ubuntu Release Status
php-league-commonmark 26.04 LTS resolute
Vulnerable
25.10 questing Ignored end of life, was needed
24.04 LTS noble
Fixed 2.4.2-2ubuntu0.1~esm1
22.04 LTS jammy
Fixed 1.6.7-1ubuntu0.1~esm1
20.04 LTS focal
Fixed 1.3.1-1ubuntu2+esm1

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Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package Patch details
php-league-commonmark

Severity score breakdown

CVSS version:

Base score 6.3 · Medium

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N

Base score 6.1 · Medium

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

References

Related Ubuntu Security Notices (USN)

    • USN-8194-1
    • league/commonmark vulnerabilities
    • 21 April 2026

Other references

Access our resources on patching vulnerabilities