The regexp (aka regular expression) implementation in Google V8 before 5.0.71.40, as used in Google Chrome before 51.0.2704.63, mishandles external string sizes, which allows remote attackers to cause a denial of service (out-of-bounds read) via crafted JavaScript code.
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.