The asm.js implementation in Mozilla Firefox before 38.0 does not properly determine heap lengths during identification of cases in which bounds checking may…

The asm.js implementation in Mozilla Firefox before 38.0 does not properly determine heap lengths during identification of cases in which bounds checking may be safely skipped, which allows remote attackers to trigger out-of-bounds write operations and possibly execute arbitrary code, or trigger out-of-bounds read operations and possibly obtain sensitive information from process memory, via crafted JavaScript.