When SAML IdP-initiated login is enabled in Grafana Enterprise, the SAML library skips validation of the InResponseTo field on all SAML responses, including SP-initiated logins. This removes anti-replay protection, allowing an attacker who obtains a valid signed SAML assertion to replay it and gain a session as the victim user. Only instances with the allow_idp_initiated SAML setting enabled are affected; this setting is off by default and Grafana OSS is not affected.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
High
Difficult to exploit
Privileges Required
None
No 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