CVE-2026-2991

High

Published: 18 March 2026

Published

18 March 2026

Modified

22 April 2026

KEV Added

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Patch

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CVSS Score 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

EPSS Score 0.0008 24.4th percentile

Risk Priority 15 60% EPSS · 20% KEV · 20% CVSS

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 24.4th 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).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 1 other technique. What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

IA-5 Authenticator Management good match

prevent

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 Access Enforcement good match

prevent

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 Identification and Authentication (Non-organizational Users) good match

prevent

IA-8 mandates identification and authentication for non-organizational users such as patients, directly mitigating the bypass vulnerability in the patientSocialLogin function.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1078 Valid Accounts Stealth

Adversaries may obtain and abuse credentials of existing accounts as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion.

attack.mitre.org →

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.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

NVD Description

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…

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.

Deeper analysisAI

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.