pam_sm_authenticate in pam_pgsql.c in libpam-pgsql 0.6.3 does not properly consider operator precedence when evaluating the success of a pam_get_pass function call, which allows local users to gain privileges via a SIGINT signal when this function is executing, as demonstrated by a CTRL-C sequence at a sudo password prompt in an "auth sufficient pam_pgsql.so" configuration.

More... (http://nvd.nist.gov/nvd.cfm?cvename=CVE-2008-2516)