Keycloak allows users to log in using Google accounts and can be configured to only allow users from specific Google Workspace domains. A flaw was found where the token exchange feature, which allows swapping a Google token for a Keycloak token, does not check these domain restrictions. This means an attacker with a valid Google account from a different domain could bypass the security check and gain access to the Keycloak realm.
Exploitability
AV:NAC:HPR:LUI:NScope
S:UImpact
C:HI:HA:N6.8/CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:NAccess Control