CryptoLib provides a software-only solution using the CCSDS Space Data Link Security Protocol - Extended Procedures (SDLS-EP) to secure communications between a spacecraft running the core Flight System (cFS) and a ground station. A critical heap buffer overflow vulnerability was identified in the "Crypto_AOS_ProcessSecurity" function of CryptoLib versions 1.3.3 and prior. This vulnerability allows an attacker to trigger a Denial of Service (DoS) or potentially execute arbitrary code (RCE) by providing a maliciously crafted AOS frame with an insufficient length. The vulnerability lies in the function "Crypto_AOS_ProcessSecurity", specifically during the processing of the Frame Error Control Field (FECF). The affected code attempts to read from the "p_ingest" buffer at indices "current_managed_parameters_struct.max_frame_size - 2" and "current_managed_parameters_struct.max_frame_size - 1" without verifying if "len_ingest" is sufficiently large. This leads to a heap buffer overflow when "len_ingest" is smaller than "max_frame_size". As of time of publication, no known patched versions exist.