CVE-2026-123999: ION-DTN 3.6.2-4.2.0 Heap Buffer Overflow via nm_mgr AMP Rendering

NASA JPL ION-DTN 3.6.2 through 4.2.0 contains a heap-based buffer overflow in the Network Management daemon (nmmgr) string-formatting logic that allows a malicious or misconfigured agent to trigger an out-of-bounds write by sending deeply nested AMP payloads that exceed fixed-size buffer allocations through unbounded strcat operations. Attackers can transmit oversized AMP reports, tables, or macros over the UDP CLA/AMP path or trigger the flaw locally via interactive UI rendering to crash nmmgr and cause a denial of service halting telemetry collection and operator visibility.