Some vulnerabilities have been reported in Kerberos, which can be exploited by malicious users and malicious people to compromise a vulnerable system.

1) A boundary error within the implementation of the RPCSEC_GSS authentication type exists in the "svcauth_gss_validate()" function in src/lib/rpc/svc_auth_gss.c. This can be exploited to cause a stack-based buffer overflow by sending a specially crafted RPC message to a vulnerable server.

Successful exploitation potentially allows the execution of arbitrary code. Products linking to the RPC library may also be affected.

2) The "kadm5_modify_policy_internal()" function in src/lib/kadm5/srv/svr_policy.c does not correctly check return values of the "krb5_db_get_policy()" function. This can be exploited to cause a memory corruption and may potentially allow the execution of arbitrary code.

Successful exploitation requires valid user credentials and privileges to modify policies.

Vulnerability #1 is reported in krb5-1.4 through krb5-1.6.2, vulnerability #2 is reported in krb5-1.5 through krb5-1.6.2.

Solution
Update to Kerberos 1.5.5 or 1.6.3 as soon as available or apply patches.
Further details available in Customer Area

Provided and/or discovered by
1) Tenable Network Security, reported via the Zero Day Initiative.
2) Garrett Wollman, MIT CSAIL.

Changelog
Further details available in Customer Area

Original Advisory
MIT Kerberos:
http://web.mit.edu/kerberos/www/advisories/MITKRB5-SA-2007-006.txt

ZDI:
http://www.zerodayinitiative.com/advisories/ZDI-07-052.html

Other references
Further details available in Customer Area

Deep Links
Links available in Customer Area