---
id: "CVE-2026-125066"
page: "https://infrastack.ai/live/CVE-2026-125066"
kind: "vulnerability"
aliases: ["CVE-2026-125066"]
title: "FFmpeg: crafted AVI file crashes decoder via NULL pointer dereference"
severity: "medium"
cvss: 6.8
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["ffmpeg", "libavcodec", "media-processing", "package"]
not_affected_if: ["no-untrusted-media-input"]
published_at: "2026-11-09T19:16:48+00:00"
first_seen_at: "2026-11-09T19:28:15+00:00"
updated_at: "2026-11-09T19:31:47+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-125066", "first_seen_at": "2026-11-09T19:28:15+00:00"}]
exploit_sources: []
---

# FFmpeg: crafted AVI file crashes decoder via NULL pointer dereference

Link for people: https://infrastack.ai/live/CVE-2026-125066 (this .md is for agents)

FFmpeg's Cirrus Logic AccuPak (CLJR) decoder ignores a bit-reader initialization failure, so a crafted AVI file with an oversized frame causes a NULL buffer read. An attacker gets the FFmpeg process to crash when it opens the file.

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

## Timeline

- 2026-11-09T19:28:15+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-125066

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-null-pointer-dereference-in-cljr-video-decoder
- [fix] Patch: github.com https://github.com/FFmpeg/FFmpeg/commit/d40c1b12811814fc6c2d0816527b003d8510ea06

## From the sources

FFmpeg through 9.0.2 contains a NULL pointer dereference vulnerability in the Cirrus Logic AccuPak (CLJR) decoder in libavcodec/cljrdec.c because decode_frame() ignores init_get_bits() failure. Attackers can supply a crafted AVI file with a 2^28-byte CLJR frame that overflows the bit count, causing reads from a NULL buffer and crashing the process.

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