An authentication bypass vulnerability exists in the GlobalProtect SSL VPN component of Palo Alto Networks PAN-OS software that allows an attacker to bypass all client certificate checks with an invalid certificate. A remote attacker can successfully authenticate as any user and gain access to restricted VPN network resources when the gateway or portal is configured to rely entirely on certificate-based authentication.
Impacted features that use SSL VPN with client certificate verification are:
GlobalProtect Clientless VPN
In configurations where client certificate verification is used in conjunction with other authentication methods, the protections added by the certificate check are ignored as a result of this issue.
This issue impacts:
PAN-OS 8.1 versions earlier than PAN-OS 8.1.17;
PAN-OS 9.0 versions earlier than PAN-OS 9.0.11;
PAN-OS 9.1 versions earlier than PAN-OS 9.1.5;
PAN-OS 10.0 versions earlier than PAN-OS 10.0.1.