FFmpeg RASC Decoder OOB Heap Write via Malformed Frame
CVE-2026-58049 Published on June 28, 2026
FFmpeg - Out-of-Bounds Write in RASC Decoder decode_dlta()
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.
Vulnerability Analysis
CVE-2026-58049 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and a high impact on availability.
Weakness Type
What is a Memory Corruption Vulnerability?
The software writes data past the end, or before the beginning, of the intended buffer. Typically, this can result in corruption of data, a crash, or code execution. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent write operation then produces undefined or unexpected results.
CVE-2026-58049 has been classified to as a Memory Corruption vulnerability or weakness.
Products Associated with CVE-2026-58049
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Affected Versions
FFmpeg:- Before and including bcd2c69e087a09b07cf45c6bd2428ee1ccb2925c is affected.