A buffer overflow condition exists in the OpenSSH server. The condition is exploitable by attackers with valid user credentials in versions 2.9.9 and higher. Exploitation does not require valid user credentials in versions prior to 2.9.9.
The vulnerability is related to the handling of Kerberos 4 TGT/AFS tokens passed by the client. An unbounded string copy operation may result in a stack overflow if the TGT/token data is malformed.