Keycloak is widely used; authorization bypass enables cross-tenant resource access and token issuance; high-risk impact.
CVE-2026-4636
Authenticated UMA user can bypass policy to access victim-owned resources.
Is CVE-2026-4636 being exploited?
Not confirmed. CVE-2026-4636 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.35% probability of exploitation in the next 30 days.
How severe is CVE-2026-4636?
CVE-2026-4636 is rated Low with a CVSS score of 3.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-4636?
Yes. A fix has been recorded for CVE-2026-4636. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-4636 affect?
CVE-2026-4636 affects Keycloak. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-4636?
Apply Keycloak updates when released; review UMA policies and access controls.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Bypass UMA validation to include others' resource IDs; obtain RPT and access/modify victim resources.
Patch when possible