CVE-2016-3176: Salt Insecure configuration of PAM external authentication service

The vulnerability stems from improper validation of the PAM service name during authentication. When PAM external auth is enabled, Salt's authentication mechanism should enforce the use of a pre-configured service name. The PAMAuth.authenticate function would be responsible for handling authentication requests, and if it accepted a client-specified 'service' parameter without checking against the configured value, this would allow service substitution. This matches the CWE-287 (Improper Authentication) pattern where client-controlled input directly influences authentication mechanisms without proper validation. The confidence is high because this is the logical location for PAM authentication handling and the vulnerability description explicitly mentions client-specified service parameters as the attack vector.