Integer overflow in Ffmpeg
CVE-2026-96611
FFmpeg before 9.0 has a signed integer overflow in libavformat/mov.c. In mov_read_ispe(), uint32_t width/height values from a crafted HEIF ispe box are stored into signed int fields without bounds checking, allowing values exceeding INT_MAX to become negative. In read_image_grid(), accumulating these values causes signed integer overflow (undefined behavior per C17 section 6.5), which on x86 wraps to a small positive value, bypassing downstream validity checks.
Vulnerability class: Integer Overflow
Published .
CVSS v3 metric
CVSS v3 base score 6.9 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-96611?
- CVE-2026-96611 is a medium-severity vulnerability in Ffmpeg, classified under Integer Overflow or Wraparound. CVSS score: 6.9/10. Published 2026-09-23.
- How severe is CVE-2026-96611?
- Medium severity. CVSS v3 base score is 6.9 out of 10.