---
id: "CVE-2026-125206"
page: "https://infrastack.ai/live/CVE-2026-125206"
kind: "vulnerability"
aliases: ["CVE-2026-125206"]
title: "FFmpeg: ProRes 4444 encoder reads out-of-bounds memory into output video"
severity: "low"
cvss: 2.5
epss: null
exploited: false
status: "open"
category: "other"
products: []
ecosystems: []
tags: ["ffmpeg", "other", "prores", "video-encoding"]
not_affected_if: ["no-prores-4444-alpha", "no-untrusted-input"]
published_at: "2026-11-09T19:16:57+00:00"
first_seen_at: "2026-11-09T19:28:18+00:00"
updated_at: "2026-11-09T19:33:45+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-125206", "first_seen_at": "2026-11-09T19:28:18+00:00"}]
exploit_sources: []
---

# FFmpeg: ProRes 4444 encoder reads out-of-bounds memory into output video

Link for people: https://infrastack.ai/live/CVE-2026-125206 (this .md is for agents)

FFmpeg through 9.0.2 has an out-of-bounds read in the prores_ks encoder's get_alpha_data() function, which reads memory before the blocks buffer for interlaced frames with odd heights. An attacker who supplies a crafted video with alpha and odd height can get out-of-bounds memory copied into the output alpha plane.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed FFmpeg version with `ffmpeg -version`; the flaw is stated to affect versions through `9.0.2`.
- Look for encoding of ProRes 4444 with alpha from untrusted input in your pipelines.

## Fix

- A patch is linked from the advisory references; the sources do not state a fixed version.

## Timeline

- 2026-11-09T19:28:18+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-125206

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-out-of-bounds-read-via-prores-ks-interlaced-alpha-encoding
- [fix] Patch: github.com https://github.com/FFmpeg/FFmpeg/commit/9edd06f8612c242b83bf9e3d14aa85180015a211

## From the sources

FFmpeg through 9.0.2 contains an out-of-bounds read vulnerability in the prores_ks encoder's get_alpha_data() that reads before the blocks buffer for interlaced frames with odd heights. Attackers can supply video with alpha and odd height encoded to interlaced ProRes 4444, causing out-of-bounds memory to be encoded into the output alpha plane.

---

_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_