Auth bypass in Red Hat Build Of Keycloak
CVE-2026-37978
A flaw was found in Keycloak. A low-privilege administrator with the 'view-clients' role can exploit this by invoking the 'evaluate-scopes' Admin API endpoints with an arbitrary user ID (userId) parameter. This vulnerability allows for cross-role personally identifiable information (PII) leakage, enabling unauthorized visibility into user identities and authorizations across the realm. Exploitation is possible remotely via network access to the Admin API.
Vulnerability class: IDOR (Insecure Direct Object Reference)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.9 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.005 (37.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 37.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.005 · change: +0.001
Affected products
- Red Hat Build Of Keycloak
- Red Hat Build Of Keycloak 26.4 — versions 26.4.12-1, 26.4-17
- Red Hat Build Of Keycloak 26.4.12
- Red Hat Build Of Keycloak
Weakness classification (CWE)
References
- access.redhat.com/security/cve/CVE-2026-37978 (vdb-entry, Vendor Advisory)
- bugzilla.redhat.com/show_bug.cgi (issue-tracking, Vendor Advisory)
- access.redhat.com/errata/RHSA-2026:19597 (vendor-advisory, Vendor Advisory)
- access.redhat.com/errata/RHSA-2026:19596 (vendor-advisory, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-37978?
- CVE-2026-37978 is a medium-severity vulnerability in Red Hat Build Of Keycloak, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 4.9/10. Published 2026-05-19.
- How severe is CVE-2026-37978?
- Medium severity. CVSS v3 base score is 4.9 out of 10.