CVE intelligence and bounded remediation

CVE-2026-30927 — Admidio is an open-source user management solution

Medium CVSS 5.4

Admidio is an open-source user management solution. Prior to 5.0.6, in modules/events/events_function.php, the event participation logic allows any user who can participate in an event to register OTHER users by manipulating the user_uuid GET parameter. The condition uses || (OR), meaning if possibleToParticipate() returns true (event is open for participation), ANY user - not just leaders - can specify a different user_uuid and register/cancel participation for that user. The code then operates on $user->getValue('usr_id') (the target user from user_uuid) rather than the current user. This vulnerability is fixed in 5.0.6.

Severity
Medium
CVSS
5.4 (3.1)
Published
2026-03-10
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-639

Affected products

  • admidio / admidio

Matched remediation archetype

Authorization bypass, IDOR, and cross-tenant access

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Map object and action authorization checks across API, UI, batch, import/export, and background-job paths.
  • Identify tenant, ownership, role, and policy boundaries for affected resources and administrative operations.
  • Use synthetic fixtures to compare intended access matrices without accessing another user's real data.

Remediate safely

  • Enforce server-side authorization at each resource access and state transition using the authenticated principal and trusted tenant context.
  • Scope data queries by tenant and ownership; treat client-supplied identifiers, roles, and policy claims as untrusted.
  • Add deny-by-default policy tests for horizontal and vertical access across every affected transport.

Authoritative sources

Complete CVE record and remediation plan

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