CVE-2026-125218 FFmpeg through 9.0.2 APNG Encoder Heap Buffer Overflow via encode_apng()

High 7.3 Published 9 Nov 2026 Updated 9 Nov 2026

Exploited in the wild: Not known
Fix: None listed

What is CVE-2026-125218?

CVE-2026-125218 is a high-severity vulnerability in FFmpeg, published on 9 Nov 2026.

Official description

FFmpeg through 9.0.2 contains a heap buffer overflow vulnerability in the APNG encoder's encode_apng() function in libavcodec/pngenc.c when frame size changes mid-stream. Attackers can supply crafted media whose resolution grows mid-stream, causing APNG_DISPOSE_OP_BACKGROUND memset writes past prev_frame and crashing or corrupting heap memory in transcoding applications.

Weakness: CWE-122

Which versions are affected by CVE-2026-125218?

How do I fix CVE-2026-125218?

No fix has been published for CVE-2026-125218 yet. Limit exposure of the affected software until one is available.

Is CVE-2026-125218 being exploited?

There is no known exploitation of CVE-2026-125218 in the wild and no public exploit code.

Sources

Also known as GHSA-hp56-qgqc-859j, UBUNTU-CVE-2026-125218.