CVE-2026-125259 FFmpeg through 9.0.2 Heap Buffer Overflow via ProRes prores_ks Encoder

High 8.5 Published 9 Nov 2026 Updated 10 Nov 2026

Exploited in the wild: Not known
Fix: None listed

What is CVE-2026-125259?

CVE-2026-125259 is a high-severity vulnerability in FFmpeg, published on 9 Nov 2026.

Official description

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.

Weakness: CWE-190

Which versions are affected by CVE-2026-125259?

How do I fix CVE-2026-125259?

No fix has been published for CVE-2026-125259 yet. Limit exposure of the affected software until one is available.

Is CVE-2026-125259 being exploited?

There is no known exploitation of CVE-2026-125259 in the wild and no public exploit code.

Sources

Also known as GHSA-pr5x-4ggj-w5wj, UBUNTU-CVE-2026-125259.