CVE-2026-4636: Redhat Build Of Keycloak vulnerability (CVSS 8.1)

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.

CVSS 3.1 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredLow

User interactionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityHigh

AvailabilityNone

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

Affected products

Redhat Build Of Keycloak26.2.15 · 26.2 · 26.4.11 · 26.4

Remediation

No fixed version is recorded in the NVD data. Check the vendor advisory for the latest guidance.

Patch & vendor advisories

References

https://access.redhat.com/errata/RHSA-2026:6475Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:6476Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:6477Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:6478Vendor Advisory
https://access.redhat.com/security/cve/CVE-2026-4636Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2450251ExploitIssue TrackingVendor Advisory
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4636.json

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2026-4636 being actively exploited?

CVE-2026-4636 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.48%.

How severe is CVE-2026-4636?

CVE-2026-4636 has a CVSS 3.1 base score of 8.1, rated high. EPSS estimates a 0.48% probability of exploitation.

Which products are affected by CVE-2026-4636?

Affected products include Redhat Build Of Keycloak.

How do I fix CVE-2026-4636?

Apply the vendor's patch or advisory guidance, then verify no affected versions remain across your devices.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-4636 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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