commit 983c5c36e5f109512ed1af38a329d0b5d0967498 (refs/remotes/origin/v4)
Author: flozilla <fishyflow@gmail.com>
Date:   2018-10-24 14:12:01 +0200

    Fix memory leak when parsing SNMP packet (#313)
    
    SNMP queries denied by snmp_access rules and queries with certain
    unsupported SNMPv2 commands were leaking a few hundred bytes each. Such
    queries trigger "SNMP agent query DENIED from..." WARNINGs in cache.log.

diff --git a/src/snmp_core.cc b/src/snmp_core.cc
index ad83935..281da51 100644
--- a/src/snmp_core.cc
+++ b/src/snmp_core.cc
@@ -409,6 +409,7 @@ snmpDecodePacket(SnmpRequest * rq)
             snmpConstructReponse(rq);
         } else {
             debugs(49, DBG_IMPORTANT, "WARNING: SNMP agent query DENIED from : " << rq->from);
+            snmp_free_pdu(PDU);
         }
         xfree(Community);