krb5: UDP ping-pong flaw in kpasswd

A flaw in certain programs that handle UDP traffic was discovered and assigned the name CVE-1999-0103 (that CVE specifically mentions echo and chargen as vulnerable). In 2002, a Nessus plugin was included [1] that reference this CVE name, but was for the kpasswd service. Until recently, this issue had not been reported upstream. This issue has since been reported upstream [2] and is now fixed [3].

If a malicious remote user were to spoof their IP address to that of another server running kadmind with the password change port (kpasswd, port 464), or to the target server's IP address itself), kpasswd will pass UDP packets to the spoofed address and reply each time. This can be used to consume bandwidth and CPU on the affected servers running kadmind.

This should be fixed in the krb5-1.11.3 release.

[1] http://marc.info/?l=nessus&m=102418951803893&w=2
[2] http://krbdev.mit.edu/rt/Ticket/Display.html?id=7637
[3] https://github.com/krb5/krb5/commit/cf1a0c411b2668...