An integer underflow exists in the External Term Format (ETF) decoder within the `BIT BINARY EXT` tag (77) handler. When the decoder accepts an encoding where both length and trailing-bits fields are set to zero, the bitstring size computation underflows an unsigned integer. This results in an extremely large value (approximately 2^64) being passed as a memory allocation size, causing the allocator to abort the entire node. This VM-level abort cannot be intercepted by supervision trees, try/catch blocks, or the `[safe]` option in `binary to term/2`. Applications decoding ETF from untrusted sources using `binary to term/1,2` or `enif binary to term()` are exposed. The Erlang distribution protocol also uses this code path, though it is intended for trusted networks.