GHSA-h8gr-qwr6-m9gx: Admidio is Missing CSRF Protection on Role Membership Date Changes
SummaryThe `save_membership` action in `modules/profile/profile_function.php` saves changes to a member's role membership start and end dates but does not validate the CSRF token. The handler checks `stop_membership` and `remove_former_membership` against the CSRF token but omits `save_membership` from that check. Because membership UUIDs appear in the HTML source visible to authenticated users, an attacker can embed a crafted POST form on any external page and trick a role leader into submitting it, silently altering membership dates for any member of roles the victim leads.DetailsCSRF Check Is Absent for save_membershipFile: `D:/bugcrowd/admidio/repo/modules/profile/profile_function.php`, lines 40-42The CSRF guard covers only two of the three mutative modes:The `save_membership` mode is missing from this array. The handler then proceeds to read dates from `$_POST` and update the database without any token verification:File: `D:/bugcrowd/admidio/repo/modules/profile/profile_function.php`, lines 131-169The Form Does Generate a CSRF Token (Not Validated)File: `D:/bugcrowd/admidio/repo/modules/profile/roles_functions.php`, lines 218-241The membership date form is created via `FormPresenter`, which automatically injects an `adm_csrf_token` hidden field into every form. However, the server-side `save_membership` handler never retrieves or validates this token. An attacker's forged form does not need to include the token at all, since the server does not check it.Who Can Be Exploited as the CSRF VictimFile: `D:/bugcrowd/admidio/repo/src/Roles/Entity/Role.php`, lines 98-121The `allowedToAssignMembers()` check grants write access to:Any user who is `isAdministratorRoles()` (role administrators), orAny user who is a leader of the target role when the role has `rol_leader_rights` set to `ROLE_LEADER_MEMBERS_ASSIGN` or `ROLE_LEADER_MEMBERS_ASSIGN_EDIT`Role leaders are not system administrators. They are regular members who have been designated as group leaders (e.g., a sports team captain or committee chair). This represents a low-privilege attack surface.UUIDs Are Discoverable from HTML SourceThe save URL for the membership date form is embedded in the profile page HTML:Any authenticated member who can view a profile page can extract both UUIDs from the page source.PoCThe attacker hosts the following HTML page and tricks a role leader into visiting it while logged in to Admidio:Expected result: The target member's role membership dates are overwritten to 2000-01-01 through 2000-01-02, effectively terminating their active membership immediately (end date is in the past).Note: No `adm_csrf_token` field is required because the server does not validate it for `save_membership`.Impact**Unauthorized membership date manipulation:** A role leader's session can be silently exploited to change start and end dates for any member of roles they lead. Setting the end date to a past date immediately terminates the member's active participation.**Effective access revocation:** Membership in roles controls access to role-restricted features (events visible only to role members, document folders with upload rights, and mailing list memberships). Revoking membership via CSRF removes these access rights.**Covert escalation:** An attacker could also extend a restricted membership period beyond its authorized end date, maintaining access for a user who should have been deactivated.**No administrative approval required:** The impact occurs silently on the victim's session with no confirmation dialog or notification email.Recommended FixFix 1: Add `save_membership` to the existing CSRF validation checkFix 2: Use the form-object validation pattern (consistent with other write endpoints)
CVSS v3.1: 5.7