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Mozilla Foundation Security Advisory 2015-142

DOS due to malformed frames in HTTP/2

December 15, 2015
Stuart Larsen
Firefox, Firefox OS
Fixed in
  • Firefox 43
  • Firefox OS 2.5


Security researcher Stuart Larsen reported two issues with HTTP/2 resulting in integer underflows that lead to intentional aborts when the errors are detected.

In the first issue, if a malformed HTTP2 header frame is received with only a single byte, an integer underflow can be created in some circumstances. In the second issue, a malformed HTTP2 PushPromse frame is received and the length of the decompressed buffer is miscalculated, leading to another integer underflow. In both of these instances, more memory is allocated than is allowed, triggering assertions and intentional aborts (a denial of service) but no exploitable crashes.