CVE-2026-2991
Published: 18 March 2026
Summary
CVE-2026-2991 is a high-severity Improper Authentication (CWE-287) vulnerability in Wordpress (inferred from references). Its CVSS base score is 7.3 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 20.6th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 AC-3 (Access Enforcement) and IA-5 (Authenticator Management).
Deeper analysis
CVE-2026-2991 is an authentication bypass vulnerability affecting the KiviCare – Clinic & Patient Management System (EHR) plugin for WordPress in all versions up to and including 4.1.2. The issue stems from the `patientSocialLogin()` function, which fails to verify the social provider access token before authenticating a user. This flaw, classified under CWE-287 (Improper Authentication), has a CVSS v3.1 base score of 7.3 (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L), indicating high severity due to its network accessibility and lack of prerequisites.
Unauthenticated attackers can exploit this vulnerability remotely by supplying only a target patient's email address and an arbitrary value for the access token, thereby logging in as that patient without any valid credentials. Successful exploitation grants access to sensitive medical records, appointments, prescriptions, and billing information, resulting in a PII/PHI breach. Additionally, authentication cookies are set prior to role checks, exposing cookies for non-patient users—including administrators—in the HTTP response headers, even when a 403 Forbidden status is returned.
Advisories and references, including the Wordfence threat intelligence report and WordPress plugin trac browser links to AuthController.php lines 1852 and 284, along with changeset 3467409, highlight the issue and point to the code changes addressing the token verification deficiency. Security practitioners should update to a plugin version beyond 4.1.2 to mitigate the risk.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-12838
Vulnerability details
The KiviCare – Clinic & Patient Management System (EHR) plugin for WordPress is vulnerable to Authentication Bypass in all versions up to, and including, 4.1.2. This is due to the `patientSocialLogin()` function not verifying the social provider access token before…
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authenticating a user. This makes it possible for unauthenticated attackers to log in as any patient registered on the system by providing only their email address and an arbitrary value for the access token, bypassing all credential verification. The attacker gains access to sensitive medical records, appointments, prescriptions, and billing information (PII/PHI breach). Additionally, authentication cookies are set before the role check, meaning the auth cookies for non-patient users (including administrators) are also set in the HTTP response headers, even though a 403 response is returned.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
The vulnerability is an authentication bypass in a public-facing WordPress plugin (T1190: Exploit Public-Facing Application), enabling unauthenticated attackers to impersonate any registered patient and use valid accounts (T1078: Valid Accounts) to access sensitive data.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
IA-5 requires proper management and verification of authenticators, directly preventing authentication bypass by mandating validation of the social provider access token before user authentication.
AC-3 enforces approved authorizations in accordance with access control policies, preventing unauthorized access to patient accounts and sensitive PII/PHI by ensuring authentication succeeds only with valid credentials.
IA-8 mandates identification and authentication for non-organizational users such as patients, directly mitigating the bypass vulnerability in the patientSocialLogin function.