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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.

PUBLISHED Reserved 2026-03-23 | Published 2026-04-02 | Updated 2026-04-02 | Assigner redhat




HIGH: 8.1CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Problem types

Incorrect Behavior Order: Authorization Before Parsing and Canonicalization

Product status

Default status
affected

26.2.15-1 (rpm) before *
unaffected

Default status
affected

26.2-18 (rpm) before *
unaffected

Default status
affected

26.2-18 (rpm) before *
unaffected

Default status
unaffected

Default status
affected

26.4.11-1 (rpm) before *
unaffected

Default status
affected

26.4-14 (rpm) before *
unaffected

Default status
affected

26.4-14 (rpm) before *
unaffected

Default status
unaffected

Timeline

2026-03-23:Reported to Red Hat.
2026-04-02:Made public.

References

access.redhat.com/errata/RHSA-2026:6475 (RHSA-2026:6475) vendor-advisory

access.redhat.com/errata/RHSA-2026:6476 (RHSA-2026:6476) vendor-advisory

access.redhat.com/errata/RHSA-2026:6477 (RHSA-2026:6477) vendor-advisory

access.redhat.com/errata/RHSA-2026:6478 (RHSA-2026:6478) vendor-advisory

access.redhat.com/security/cve/CVE-2026-4636 vdb-entry

bugzilla.redhat.com/show_bug.cgi?id=2450251 (RHBZ#2450251) issue-tracking

cve.org (CVE-2026-4636)

nvd.nist.gov (CVE-2026-4636)

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