CVE-2026-4636: redhat build_of_keycloak

Vulnerability summary

CVE-2026-4636 is a high (CVSS 8.1) vulnerability in redhat build_of_keycloak. EPSS estimates a 0.48% chance of exploitation in the next 30 days, higher than 40.6% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 02-04-2026
   PublishedVulnerability first disclosed.
2. 15-07-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-551Incorrect Behavior Order: Authorization Before Parsing and CanonicalizationIf a web server does not fully parse requested URLs before it examines them for authorization, it may be possible for an attacker to bypass authorization protection.