A flaw was found in the first broker login flow of Keycloak. When a user confirms an account-linking request from a different browser, a temporary proof is created to validate the link. However, this proof is not properly cleared after the link is established or when the user later manually removes the link.
An attacker who controls the external identity can exploit this leftover proof to silently re-establish the link and gain unauthorized access to the victims account without any further confirmation.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
High
Difficult to exploit
Privileges Required
Low
Basic privileges needed
User Interaction
Required
User action required
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
Vulnerable Products
red hat:red hat single sign-on 7
red hat:red hat build of keycloak