CVE-2010-4020
MIT Kerberos 5 (aka krb5) 1.8.x through 1.8.3 does not reject RC4 key-derivation checksums, which might allow remote authenticated users to forge a (1) AD-SIGNEDPATH or (2) AD-KDC-ISSUED signature, and possibly gain privileges, by leveraging the small key space that results from certain one-byte stream-cipher operations.
Date published : 2010-12-02
http://lists.apple.com/archives/security-announce/2011/Mar/msg00006.html