Memory corruption via crafted RASC video stream

Summary

FFmpeg's RASC video decoder (decode_dlta in libavcodec/rasc.c) performs 32-bit reads and writes at the row cursor before the NEXT_LINE row-boundary check and validates the DLTA region in pixel rather than byte units, so a DLTA run on a PAL8 frame can access several bytes past the row allocation. A crafted media stream using the RASC FourCC, decoded by libavcodec, triggers a bitstream-controlled out-of-bounds heap write and adjacent out-of-bounds read, leading to memory corruption. A flaw was found in FFmpeg's RASC video decoder. A remote attacker could exploit this by providing a crafted media stream using the RASC FourCC (Four Character Code), which is then decoded by libavcodec. This vulnerability triggers a bitstream-controlled out-of-bounds heap write and an adjacent out-of-bounds read, leading to memory corruption. This can result in a denial of service or potentially arbitrary code execution. The vulnerability in FFmpeg's RASC video decoder is rated as Important. This flaw allows a remote attacker to cause memory corruption, potentially leading to denial of service or arbitrary code execution, by providing a specially crafted media stream. Red Hat products utilizing FFmpeg for RASC video decoding are at risk if they process untrusted media content. Red Hat severity: Important — CVSS 7.6 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H). Weakness: CWE-787. No fixing RHSA erratum has published yet; monitor the Red Hat CVE page and patch when it ships.