Updated Kerberos 5 (krb5) packages which correct buffer overflows in the krb5_aname_to_localname function are now available.
Kerberos is a network authentication system. Bugs have been fixed in the krb5_aname_to_localname library function. Specifically, buffer overflows were possible for all Kerberos versions up to and including 1.3.3. The krb5_aname_to_localname function translates a Kerberos principal name to a local account name, typically a UNIX username. This function is frequently used when performing authorization checks. If configured with mappings from particular Kerberos principals to particular UNIX user names, certain functions called by krb5_aname_to_localname will not properly check the lengths of buffers used to store portions of the principal name. If configured to map principals to user names using rules, krb5_aname_to_localname would consistently write one byte past the end of a buffer allocated from the heap. The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name CAN-2004-0523 to this issue. Only configurations which enable the explicit mapping or rules-based mapping functionality of krb5_aname_to_localname() are vulnerable. These configurations are not the default. Users of Kerberos are advised to upgrade to these erratum packages which contain backported security patches to correct these issues.