Buffer overflow in Ffmpeg

CVE-2026-65704

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.

EPSS: 0.002 (7.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

Affected products

  • Ffmpeg — versions 0, de771bd52774a52d45b0e2c82e56995a1ef40df7

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-65704?
CVE-2026-65704 is a high-severity vulnerability in Ffmpeg, classified under Integer Underflow. CVSS score: 7.8/10. Published 2026-07-23.
How severe is CVE-2026-65704?
High severity. CVSS v3 base score is 7.8 out of 10.