CVE-2026-93424

FastNetMon is a high-performance DDoS detector and sensor. In version 1.2.9 and earlier, peer find template() in src/netflow plugin/netflow collector.cpp and src/netflow plugin/netflow v9 collector.cpp returns a pointer into global netflow9 templates after releasing the cache mutex. On deployments with at least two entries in netflow ports, concurrent template redefinition and data-flowset processing can let add update peer template() reassign the template and free its records vector while another listener dereferences the escaped pointer. An unauthenticated sender that can reach both NetFlow/IPFIX listener ports can trigger a heap-use-after-free and reliably crash FastNetMon. No fixed release is available as of this review.