---
id: "CVE-2026-125071"
page: "https://infrastack.ai/live/CVE-2026-125071"
kind: "vulnerability"
aliases: ["CVE-2026-125071"]
title: "FFmpeg: oversized JV video packet crashes decoder with a NULL dereference"
severity: "medium"
cvss: 5.7
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["ffmpeg", "libavcodec", "media-processing", "package"]
not_affected_if: ["no-jv-decoding", "trusted-input-only"]
published_at: "2026-11-09T19:16:49+00:00"
first_seen_at: "2026-11-09T19:28:15+00:00"
updated_at: "2026-11-09T19:32:08+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-125071", "first_seen_at": "2026-11-09T19:28:15+00:00"}]
exploit_sources: []
---

# FFmpeg: oversized JV video packet crashes decoder with a NULL dereference

Link for people: https://infrastack.ai/live/CVE-2026-125071 (this .md is for agents)

FFmpeg through 9.0.2 has a NULL pointer dereference in the JV video decoder (libavcodec/jvdec.c). An attacker who supplies an oversized JV packet through the libavcodec API can crash the application, causing denial of service.

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

## How to check

- Check whether the application links FFmpeg libavcodec and which version it ships, for example with `ffmpeg -version`
- Confirm whether the application decodes untrusted JV video input

## Timeline

- 2026-11-09T19:28:15+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-125071

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-null-pointer-dereference-in-jv-video-decoder
- [fix] Patch: github.com https://github.com/FFmpeg/FFmpeg/commit/839c93f261cd3e1719edfac4244a2d0055ce8841

## From the sources

FFmpeg through 9.0.2 contains a NULL pointer dereference vulnerability in libavcodec/jvdec.c that allows attackers to crash applications by supplying oversized JV video packets. Attackers can pass a roughly 268435460-byte packet through the libavcodec API, overflowing the bit count so decode_frame() reads from a NULL buffer and causes denial of service.

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