CVE-2026-11800: A flaw was found in Keycloak. This JWT algorithm confusion vulnerability in the JWT Authorization Grant flow allows an attacker with valid client credentials…

PriorityP354high8.1CVSS 3.1

AVNACLPRLUINSUCHIHAN

EPSS

0.30%

21.6th percentile

A flaw was found in Keycloak. This JWT algorithm confusion vulnerability in the JWT Authorization Grant flow allows an attacker with valid client credentials to bypass signature verification. By forging an assertion, the attacker can create unauthorized access tokens. This enables the attacker to impersonate any federated user linked to the affected Identity Provider, leading to unauthorized access and potential privilege escalation.

Affected

5 ranges

Vendor	Product	Version range	Fixed in
redhat	build_of_keycloak	>= 26.6 < 26.6.4	26.6.4
rhbk	keycloak-operator-bundle_26.6.4-2	—	—
rhbk	keycloak-rhel9	—	—
rhbk	keycloak-rhel9-operator_26.6-8	—	—
rhbk	keycloak-rhel9_26.6-8	—	—

CVSS provenance

nvdv3.18.1HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

vendor_redhat8.1HIGH

Stop checking back — get the weekly exploitation signal.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.