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.
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.002 (7.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 7th percentile — 7.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
- Ffmpeg — versions 0, de771bd52774a52d45b0e2c82e56995a1ef40df7
Weakness classification (CWE)
References
- code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23767 (issue-tracking, Patch, Issue Tracking)
- code.ffmpeg.org/FFmpeg/FFmpeg/commit/de771bd52774a52d45b0e2c82e56995a1ef40df7 (Patch, patch)
- www.vulncheck.com/advisories/ffmpeg-out-of-bounds-write-via-ty-demuxer-and-shor… (Third Party Advisory, third-party-advisory)
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.