CVE-2026-30884: Mdjnelson Moodle-Mod Customcert

Critical severity, CVSS 9.6. EPSS: 0.3% chance of exploitation in the next 30 days.

mdjnelson/moodle-mod_customcert is a Moodle plugin for creating dynamically generated certificates with complete customization via the web browser. Prior to versions 4.4.9 and 5.0.3, a teacher who holds `mod/customcert:manage` in any single course can read and silently overwrite certificate elements belonging to any other course in the Moodle installation. The `core_get_fragment` callback `editelement` and the `mod_customcert_save_element` web service both fail to verify that the supplied `elementid` belongs to the authorized context, enabling cross-course information disclosure and data tampering. Versions 4.4.9 and 5.0.3 fix the issue.

Affected products

• Mdjnelson Moodle-Mod Customcert: before 4.4.9 (fixed in 4.4.9); from 5.0.0, before 5.0.3 (fixed in 5.0.3)

Published 2026-03-18. Last modified 2026-06-17.