Out-of-Bounds Write in RASC Decoder in FFmpeg Media Framework
CVE-2026-58049

8.8HIGH

Key Information:

Vendor

Ffmpeg

Status
Ffmpeg
Vendor
CVE Published:
28 June 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-58049?

The RASC video decoder within FFmpeg's libavcodec framework has a vulnerability that allows for an out-of-bounds write. This issue arises from improper handling of row cursor operations, specifically 32-bit reads and writes occurring before a necessary row-boundary check. Additionally, it wrongly validates the DLTA region in pixels instead of bytes. An attacker can exploit this flaw using a carefully crafted media stream targeting the RASC FourCC, leading to potential memory corruption due to a bitstream-controlled out-of-bounds heap write and adjacent out-of-bounds read.

Affected Version(s)

FFmpeg 0

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-58049 - Proof of Concept

References

https://github.com/bikini/exploitarium/tree/main/ffmpeg-r...
exploitthird-party-advisory
https://github.com/FFmpeg/FFmpeg/blob/master/libavcodec/r...
product
https://www.vulncheck.com/advisories/ffmpeg-out-of-bounds...
third-party-advisory

CVSS V4

Score:
8.8
Severity:
HIGH
Confidentiality:
Low
Integrity:
Low
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

ashdfrkl
.