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CVE-2026-4636 — keycloak

CVE-2026-4636 is a CWE-551 vulnerability in keycloak. A fix is available for keycloak — see the affected versions and patch details below.

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

Also known asGHSA-f2hx-5fx3-hmcv
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • A successful exploit gives an attacker total control of the affected component, not partial access.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-4636.

EPSS Exploitation Probability

via FIRST.org ↗
0.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs38th percentile — riskier than 38% of all scored CVEsHighest risk
0.00%0.33%0.66%0.98%0.0%0.4%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected
📦keycloak

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Bitnami packages — download data is not available via public APIs for these ecosystems.

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 Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦Bitnamikeycloak≥ 26.2.0&&< 26.2.126.2.1

Affected Products

1 product · 5 configurations
Application
build of keycloakredhat
4 versions
26.226.2.1526.426.4.11

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for keycloak, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update keycloak to 26.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-4636 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant

This Important vulnerability in Keycloak allows an authenticated user with the `uma_protection` role to bypass User-Managed Access (UMA) policy validation. Exploitation requires that victim users have created UMA-protected resources with `ownerManagedAccess` enabled and that authorization services are enabled on the…

Workaround published by Red Hat
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Source: Red Hat security advisory for CVE-2026-4636 (CC BY 4.0)
ProductFixed inAdvisory
Red Hat build of Keycloak 26.2rhbk/keycloak-operator-bundle:26.2.15-1RHSA-2026:6476
Red Hat build of Keycloak 26.2.15rhbk/keycloak-rhel9RHSA-2026:6475
Red Hat build of Keycloak 26.4rhbk/keycloak-operator-bundle:26.4.11-1RHSA-2026:6478
Red Hat build of Keycloak 26.4.11rhbk/keycloak-rhel9RHSA-2026:6477

Frequently Asked Questions

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.
O3 Security · Impact-Aware SCA

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CVE-2026-4636: keycloak — Fixed in 26.2.1