FastNetMon is a high-performance DDoS detector and sensor. In version 1.2.9 and earlier, the live parse_packet() callback in src/pcap_plugin/pcap_collector.cpp is registered through pcap_loop and processes captured frames when pcap = on without checking packethdr->caplen. A short frame or an attacker-controlled IPv4 header length can make the parser dereference IP or transport headers beyond the captured bytes, causing an out-of-bounds read and process termination. No fixed release is available as of this review.