CVE-2026-58049 FFmpeg - Out-of-Bounds Write in RASC Decoder decode_dlta()
A crafted media stream triggers an out-of-bounds heap write in FFmpeg's RASC decoder, potentially allowing remote code execution or denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-58049?
CVE-2026-58049 is a high-severity memory corruption vulnerability in FFmpeg, published on 28 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-787
Which versions are affected by CVE-2026-58049?
How do I fix CVE-2026-58049?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-58049 being exploited?
There is no known exploitation of CVE-2026-58049 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-58049, ECHO-d121-7767-849c, GHSA-mjxr-6gqf-w78h, JLSEC-2026-1171, UBUNTU-CVE-2026-58049.