OpenEMR through 8.2.0 contains an improper authentication vulnerability in the OAuth2 dynamic client registration endpoint that allows unauthenticated attackers to register a malicious client with system-level FHIR scopes by supplying a self-generated RSA keypair via the jwks field. Once an administrator approves the registered client, attackers can use the client_credentials grant with a self-signed JWT assertion to obtain access tokens granting read access to all FHIR resources across all patients in the system.
https://jivasecurity.com/writeups/openemr-unauth-oauth2-client-registration
Published: 2026-08-03
Updated: 2026-08-03
Base Score: 9.4
Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:N
Severity: High
Base Score: 8.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Severity: High
Base Score: 8.6
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Severity: High
EPSS: 0.00326