NASA JPL ION-DTN 2.2.1b through 4.2.0 contains an integer overflow vulnerability in the Datagram Retransmission (DGR) convergence layer that allows attackers to corrupt heap memory by sending a maliciously crafted 64-bit svcDataLength value that wraps a 32-bit allocation size calculation. Attackers can exploit the dgr_receive API's unchecked memcpy operation using synthetic datagrams or DGR traffic over internal IPC or custom transports to trigger an out-of-bounds write, leading to denial of service or potential remote code execution.