Integer overflow in Ffmpeg
CVE-2026-125259
FFmpeg through 9.0.2 contains an integer overflow vulnerability in ff_prores_kostya_encode_init() that miscalculates frame_size_upper_bound using 32-bit arithmetic for large frame dimensions. Attackers can supply a high-resolution video transcoded with the prores_ks encoder, causing encode_frame() to write slices past an undersized packet buffer and corrupt heap memory.
Vulnerability class: Integer Overflow
Published .
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
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
- code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25573 (issue-tracking)
- github.com/FFmpeg/FFmpeg/commit/439b452f9fe916a9f7d8788ab6afee8fac846b0b (patch)
- github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/proresenc_kostya_common.c (technical-description)
- github.com/FFmpeg/FFmpeg (product)
- www.vulncheck.com/advisories/ffmpeg-through-9.0.2-heap-buffer-overflow-via-pror… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-125259?
- CVE-2026-125259 is a high-severity vulnerability in Ffmpeg, classified under Integer Overflow or Wraparound. CVSS score: 7.8/10. Published 2026-11-09.
- How severe is CVE-2026-125259?
- High severity. CVSS v3 base score is 7.8 out of 10.