The get_input_token function in the SPNEGO implementation in MIT Kerberos 5 (aka krb5) 1.5 through 1.6.3 allows remote attackers to cause a denial of service (daemon crash) and possibly obtain sensitive information via a crafted length value that triggers a buffer over-read.
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.