Wes Hardaker reports through sourceforge.net forum:
SECURITY ISSUE: A bug in the getbulk handling code could
let anyone with even minimal access crash the agent. If you
have open access to your snmp agents (bad bad bad; stop doing
that!) or if you don't trust everyone that does have access to
your agents you should updated immediately to prevent
potential denial of service attacks.
Description at cve.mitre.org additionally clarifies:
Integer overflow in the netsnmp_create_subtree_cache
function in agent/snmp_agent.c in net-snmp 5.4 before
5.4.2.1, 5.3 before 5.3.2.3, and 5.2 before 5.2.5.1 allows
remote attackers to cause a denial of service (crash) via
a crafted SNMP GETBULK request, which triggers a heap-based
buffer overflow, related to the number of responses or
repeats.