Auth bypass in Mdjnelson Moodle-Mod Customcert
CVE-2026-30884
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.
Vulnerability class: IDOR (Insecure Direct Object Reference)
EPSS: 0.002 (6.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.6 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N.
Affected products
- Mdjnelson Moodle-mod_customcert — versions < 4.4.9, >= 5.0.0, < 5.0.3
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-30884?
- CVE-2026-30884 is a critical-severity vulnerability in Mdjnelson Moodle-Mod Customcert, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 9.6/10. Published 2026-03-18.
- How severe is CVE-2026-30884?
- Critical severity. CVSS v3 base score is 9.6 out of 10.