FastNetMon is a high-performance DDoS detector and sensor. In version 1.2.9 and earlier, parse_raw_packet_to_simple_packet_full() in src/simple_packet_parser_ng.cpp dereferences ipv6_extension_header_fragment_t when IpProtocolNumberIPV6_FRAG is present without first verifying that the eight-byte Fragment header remains. A crafted sFlow v5 RAW_PACKET_HEADER record can remotely reach this shared parser with the Fragment bytes omitted, causing an unauthenticated remote out-of-bounds read. The supplied harness detects the read under AddressSanitizer, but the advisory does not establish a production process crash. No fixed release is available as of this review.