Vulnerability in Red Hat Build Of Keycloak 26.2
CVE-2026-4636
A flaw was found in Keycloak. An authenticated user with the uma_protection role can bypass User-Managed Access (UMA) policy validation. This allows the attacker to include resource identifiers owned by other users in a policy creation request, even if the URL path specifies an attacker-owned resource. Consequently, the attacker gains unauthorized permissions to victim-owned resources, enabling them to obtain a Requesting Party Token (RPT) and access sensitive information or perform unauthorized actions.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.005 (40.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 40th percentile — 40.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.001
Affected products
- Red Hat Build Of Keycloak 26.2 — versions 26.2.15-1, 26.2-18
- Red Hat Build Of Keycloak 26.2.15
- Red Hat Build Of Keycloak 26.4 — versions 26.4.11-1, 26.4-14
- Red Hat Build Of Keycloak 26.4.11
- Red Hat Build Of Keycloak — versions 26.2, 26.2.15, 26.4
Weakness classification (CWE)
References
- access.redhat.com/errata/RHSA-2026:6475 (vendor-advisory, Vendor Advisory)
- access.redhat.com/errata/RHSA-2026:6476 (vendor-advisory, Vendor Advisory)
- access.redhat.com/errata/RHSA-2026:6477 (vendor-advisory, Vendor Advisory)
- access.redhat.com/errata/RHSA-2026:6478 (vendor-advisory, Vendor Advisory)
- access.redhat.com/security/cve/CVE-2026-4636 (vdb-entry, Vendor Advisory)
- bugzilla.redhat.com/show_bug.cgi (issue-tracking, Exploit, Issue Tracking, Vendor Advisory)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Frequently asked questions
- What is CVE-2026-4636?
- CVE-2026-4636 is a high-severity vulnerability in Red Hat Build Of Keycloak 26.2, classified under CWE-551. CVSS score: 8.1/10. Published 2026-04-02.
- How severe is CVE-2026-4636?
- High severity. CVSS v3 base score is 8.1 out of 10.