CVE-2026-4636

Keycloak: keycloak: uma policy bypass allows authenticated users to gain unauthorized access to victim-owned resources.

HIGH
8.1
CVSS Score
Published: April 2, 2026 at 12:45 PM UTC
Updated: October 26, 2026 at 09:10 PM UTC
1 product affected across 1 vendorBuild of Keycloak

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Severity
HIGH8.1
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Vendor states this is fixed in 26.2-18 (unaffected)
Vendor states this is fixed in 26.2.15 (unaffected)
Vendor states this is fixed in 26.2.15-1 (unaffected)
Vendor states this is fixed in 26.4-14 (unaffected)
Vendor states this is fixed in 26.4.11 (unaffected)
Vendor states this is fixed in 26.4.11-1 (unaffected)

References (7)

VDB Entryx_refsource_REDHATVendor Advisory
Source: cverecord
https://access.redhat.com/security/cve/CVE-2026-4636
Issue Trackingx_refsource_REDHATExploitVendor Advisory
Source: cverecord
https://bugzilla.redhat.com/show_bug.cgi?id=2450251
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:6477
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:6478
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:6475
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:6476

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.1HIGHredhat
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-551

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