CVE-2026-4636
HIGHDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 27% of all known CVEs.
References
Related Vulnerabilities
Other CWE-551 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2021-34429 | Medium | 5.3 | 99% | - | Fix |
| CVE-2021-28164 | Medium | 5.3 | 82% | - | Fix |
| CVE-2021-28165 | High | 7.5 | 54% | - | Fix |
| CVE-2023-23924 | Critical | 10.0 | 3.6% | - | - |
| CVE-2021-32777 | High | 8.6 | 3.3% | - | Fix |
| CVE-2026-44575 | High | 7.5 | 1.6% | - | Fix |
Common questions
How do I fix CVE-2026-4636?
Published advisories record a fix for 2 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2026-4636 being actively exploited?
Not that we know of. CVE-2026-4636 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.35% is the estimated probability that it will be exploited in the next 30 days. That is higher than 27% of all scored CVEs.
How severe is CVE-2026-4636?
CVE-2026-4636 has a CVSS v3 base score of 8.1, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-4636 affect?
Published advisories record a fix for rhbk/keycloak (Red Hat / RHEL), rhbk/keycloak (Rocky). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-15.