CVE-2026-48689
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk48th percentile - higher than 48% of all known CVEs
Summary
FastNetMon Community Edition through 1.2.9 contains an off-by-one heap-based buffer overflow in the dynamic_binary_buffer_t class. Five methods use an incorrect bounds check, allowing writing exactly one byte past the end of the heap-allocated buffer. An attacker sending network traffic (NetFlow, sFlow, IPFIX, or BGP) can trigger this overflow, potentially achieving arbitrary code execution.
Risk Assessment
An attacker can exploit this vulnerability to corrupt heap memory and achieve remote code execution on the FastNetMon server, potentially leading to full compromise of the monitoring system.
Recommendation
Upgrade FastNetMon Community Edition to version 1.2.10 or later when available, and restrict network service access to trusted sources only.
Original NVD description (English source)
FastNetMon Community Edition through 1.2.9 contains an off-by-one heap-based buffer overflow in the dynamic_binary_buffer_t class (src/dynamic_binary_buffer.hpp). Five methods (append_dynamic_buffer, append_data_as_pointer, append_data_as_object_ptr, memcpy_from_ptr, memcpy_from_object_ptr) use an incorrect bounds check of the form 'if (offset + length > maximum_internal_storage_size + 1)' instead of the correct 'if (offset + length > maximum_internal_storage_size)'. This allows writing exactly one byte past the end of the heap-allocated buffer. The class is used pervasively in BGP message encoding/decoding, NetFlow template processing, and Flow Spec NLRI construction. An attacker who can send network traffic (NetFlow, sFlow, IPFIX, or BGP) to a FastNetMon instance can trigger this overflow, potentially achieving arbitrary code execution by corrupting heap metadata. Notably, the append_byte() method uses the correct bounds check, confirming the inconsistency.