The MPEG4Extractor::parseChunk function in MPEG4Extractor.cpp in libstagefright in Android before 5.1.1 LMY48I does not validate the relationship between chunk sizes and skip sizes, which allows remote attackers to execute arbitrary code or cause a denial of service (integer underflow and memory corruption) via crafted MPEG-4 covr atoms, aka internal bug 20923261.