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 pamsetcred 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 pamsetcred operations.