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

CVE-2026-33347 · Severity: medium · CVSS 4 · Published 2026-03-19

league/commonmark has an embed extension allowed_domains bypass

Technologies: league/commonmark (Packagist). Vendors: Packagist.

Quick answers

Is CVE-2026-33347 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-33347 being exploited in the wild.
How severe is CVE-2026-33347?
Medium severity, with a CVSS score of 4, published 19 March 2026.
Which products and versions are affected?
league/commonmark (Packagist) ECOSYSTEM:introduced=2.3.0,fixed=2.8.2.
Is there a fix for CVE-2026-33347?
Yes. league/commonmark (Packagist): upgrade to 2.8.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2026-33347?
Check whether you run league/commonmark (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • league/commonmark (Packagist): upgrade to 2.8.2 or later
    composer require league/commonmark:^2.8.2

Affected products

  • league/commonmark (Packagist) ECOSYSTEM:introduced=2.3.0,fixed=2.8.2

Identifiers

  • CVE-2026-33347
  • GHSA-hh8v-hgvp-g3f5

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