The NextEPC MME <= 1.0.1 (fixed in commit a8492c9c5bc0a66c6999cb5a263545b32a4109df) contains a stack-based buffer overflow vulnerability in the Emergency Number List decoding method. An attacker may send a NAS message containing an oversized Emergency Number List value to the MME to overwrite the stack with arbitrary bytes. An attacker with a cellphone connection to any base station managed by the MME may exploit this vulnerability without having to authenticate with the LTE core.
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).