The str_unescape function in the JavaScript engine in Mozilla Firefox before 17.0, Thunderbird before 17.0, and SeaMonkey before 2.14 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash) via unspecified vectors.
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.