Keycloak is widely deployed IAM software; token forgery can grant broad unauthorized access across organizations.
CVE-2026-11800
Keycloak JWT alg confusion lets attackers forge tokens and impersonate federated users.
Is CVE-2026-11800 being exploited?
Not confirmed. CVE-2026-11800 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 0.30% probability of exploitation in the next 30 days.
How severe is CVE-2026-11800?
CVE-2026-11800 is rated High with a CVSS score of 8.1. 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-2026-11800?
Yes. A fix has been recorded for CVE-2026-11800. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-11800 affect?
CVE-2026-11800 affects Keycloak. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-11800?
Patch Keycloak when released; ensure proper JWT validation and token monitoring.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
By forging assertions, attackers bypass signature verification, impersonate federated users, and gain unauthorized access with possible privilege escalation.
Immediate action required