While investigating a system hitting OOM errors:

we found that the heap was filled with SNMP results:

Investigating the heap dump further we found that most of these results were duplicates.

Looking at the SNMP traffic on the host, we found a large number of request/response packets with the following VBs:

In this case, the agent is responding with OIDs that are equal to the requested OIDs, rather than successors of the requested OIDs.
Our SNMP tracking code does not account for this and continues to request for OIDs following the last ones received, which leads to an infinite loop.
Everytime we receive a response, the results get added to memory, which leads to the observed problems.