Russ Allbery pam-krb5 before 3.13, as used by libpam-heimdal, su in Solaris 10, and other software, does not properly handle calls to pam_setcred when running setuid, which allows local users to overwrite and change the ownership of arbitrary files by setting the KRB5CCNAME environment variable, and then launching a setuid application that performs certain pam_setcred operations.