MIT krb5 is the free implementation of the Kerberos network authentication protocol written by the Massachusetts Institute of Technology.
The send-pr.sh script creates temporary files in world-writeable directories with predictable names.
A local attacker could create symbolic links in the temporary files directory, pointing to a valid file somewhere on the filesystem. When send-pr.sh is called, this would result in the file being overwritten with the rights of the user running the utility, which could be the root user.
There is no known workaround at this time.
All MIT krb5 users should upgrade to the latest version:
# emerge sync
# emerge -pv ">=app-crypt/mit-krb5-1.3.4-r1"
# emerge ">=app-crypt/mit-krb5-1.3.4-r1"