The ff_sbr_apply function in libavcodec/aacsbr.c in FFmpeg before 2.7.2 does not check for a matching AAC frame syntax element before proceeding with Spectral Band Replication calculations, which allows remote attackers to cause a denial of service (out-of-bounds array access) or possibly have unspecified other impact via crafted AAC data.
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.