The vulnerability is an integer underflow in the function SAE_J1939_Read_Transport_Protocol_Data_Transfer of the Open SAE J1939 library. A crafted sequence number in a CAN frame can cause the function to compute a negative index, enabling attackers to write payload data to arbitrary memory locations. This arbitrary memory write could lead to remote code execution or other compromise of confidentiality, integrity, or availability. The weakness corresponds to integer underflow (CWE-191).

Systems that rely on the Open SAE J1939 library before the commit b6caf884df46435e539b1ecbf92b6c29b345bdfe (dated 2025-11-30) are affected. This includes any embedded or automotive systems that use SAE_J1939_Read_Transport_Protocol_Data_Transfer to parse CAN frames for J1939 traffic.

EPSS score is not available and the vulnerability is not listed in the CISA KEV catalog, suggesting limited public exploitation data. However, the attack vector is inferred to be an attacker who can inject crafted CAN frames onto the vehicle or robotic network. Without a patch, the risk remains significant because the exploit achieves arbitrary memory corruption. No documented exploits are known at this time, but the description flags a serious risk.