NTP is prone to a stack-based buffer-overflow vulnerability because it fails to properly bounds-check user-supplied data before copying it into an insufficiently sized buffer.
Attackers can exploit this issue to execute arbitrary code in the context of the affected application. Failed exploit attempts will result in denial-of-service conditions.
NTP 4.2.8p11 is vulnerable; other versions may also be affected.
Information
Exploit
The researcher who discovered this issue has created a proof-of-concept. Please see the references for more information.