A flaw was found in Keycloak in versions before 10.0.0, where it does not perform the TLS hostname verification while sending emails using the SMTP server. This flaw allows an attacker to perform a man-in-the-middle (MITM) attack.
Weakness
The product communicates with a host that provides a certificate, but the product does not properly ensure that the certificate is actually associated with that host.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Keycloak | Redhat | * | 10.0.0 (excluding) |
| Red Hat Single Sign On 7.3.8 | RedHat | * | |
| Red Hat Single Sign-On 7.3 for RHEL 6 | RedHat | rh-sso7-keycloak-0:4.8.20-1.Final_redhat_00001.1.el6sso | * |
| Red Hat Single Sign-On 7.3 for RHEL 7 | RedHat | rh-sso7-keycloak-0:4.8.20-1.Final_redhat_00001.1.el7sso | * |
| Red Hat Single Sign-On 7.3 for RHEL 8 | RedHat | rh-sso7-keycloak-0:4.8.20-1.Final_redhat_00001.1.el8sso | * |
Extended Description
Even if a certificate is well-formed, signed, and follows the chain of trust, it may simply be a valid certificate for a different site than the site that the product is interacting with. In order to ensure data integrity, the certificate must be valid, and it must pertain to the site that is being accessed. Even if the product attempts to check the hostname, it is still possible to incorrectly check the hostname. For example, attackers could create a certificate with a name that begins with a trusted name followed by a NUL byte, which could cause some string-based comparisons to only examine the portion that contains the trusted name.