The function ParseVP9SuperFrameIndex in common/libwebm_util.cc in libwebm through 2018-01-30 does not validate the child_frame_length data obtained from a .webm file, which allows remote attackers to cause an information leak or a denial of service (heap-based buffer over-read and later out-of-bounds write), or possibly have unspecified other impact.
Exploitability
AV:NAC:LPR:NUI:RScope
S:UImpact
C:HI:HA:H8.8/CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H