CVE-2026-124447

OpenEMR before 8.3.0 contains an insecure direct object reference vulnerability in OnsitePortalActivityController::Update() that checks the request's patientId instead of the stored record's owner. Authenticated portal patients can send PUT requests to the onsiteportalactivity API with another patient's activity id and their own patientId to disclose tableArgs and checksum data, overwrite narratives and status, and take ownership of the record.