pam_krb5 is a a Kerberos v5 PAM module.
The following vulnerabilities were discovered:
A local attacker could set an environment variable to point to a specially crafted Kerberos configuration file and launch a PAM-based setuid application to elevate privileges, or change ownership and overwrite arbitrary files.
There is no known workaround at this time.
All pam_krb5 users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=sys-auth/pam_krb5-3.12"