Vulnerability · Published Jul 23, 2026 · Assigned by VulnCheck

CVE-2026-65704FFmpeg 8.1.2 Out-of-Bounds Write via TY Demuxer and Shorten Decoder

High 7.8

In plain English

A high-severity out-of-bounds write in FFmpeg from FFmpeg. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 7% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.8High

Exploit odds (30 days)0.2%top 92.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

FFmpeg through 8.1.2 contains an out-of-bounds write vulnerability that allows attackers to cause heap corruption by supplying a crafted ffconcat file processed with the -safe 0 flag. The TY demuxer's demux_audio() function decrements packet size without bounds checking, producing a negative size value that is passed to memcpy() in shorten_decode_frame(), where conversion to size_t wraps the value to near SIZE_MAX and triggers reads beyond the source allocation and writes far beyond the Shorten decoder's bitstream buffer.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	ffmpeg	no fix listed	DEBIAN-CVE-2026-65704
Debian:13	ffmpeg	no fix listed	DEBIAN-CVE-2026-65704
Debian:14	ffmpeg	7:9.0.2-1	DEBIAN-CVE-2026-65704
Ubuntu:26.10	ffmpeg	no fix listed	UBUNTU-CVE-2026-65704

Affected products (as reported)

Vendor	Product	Versions
FFmpeg	FFmpeg	0 – through 8.1.2

Weakness: CWE-787, CWE-191 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

References

Pull Request issue-tracking
Patch Commit patch
https://www.vulncheck.com/advisories/ffmpeg-out-of-bounds-write-via-ty-demuxer-and-shorten-decoder third-party-advisory