---
id: "CVE-2026-125073"
page: "https://infrastack.ai/live/CVE-2026-125073"
kind: "vulnerability"
aliases: ["CVE-2026-125073"]
title: "FFmpeg: crafted IMC audio file hangs decoder at full CPU"
severity: "medium"
cvss: 6.8
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["ffmpeg", "media-processing", "runtime", "self-hosted"]
not_affected_if: ["no-imc-iac-decoding", "trusted-input-only"]
published_at: "2026-11-09T19:16:50+00:00"
first_seen_at: "2026-11-09T19:28:15+00:00"
updated_at: "2026-11-09T19:31:39+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-125073", "first_seen_at": "2026-11-09T19:28:15+00:00"}]
exploit_sources: []
---

# FFmpeg: crafted IMC audio file hangs decoder at full CPU

Link for people: https://infrastack.ai/live/CVE-2026-125073 (this .md is for agents)

FFmpeg's IMC decoder in libavcodec/imc.c enters an infinite loop in bit_allocation() when an audio block has a negative bit budget. An attacker who supplies a crafted IMC or IAC audio file can hang decoding and consume 100% CPU.

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

## How to check

- Run `ffmpeg -version` and compare against the fixed release in the product ranges (unknown in the sources).
- Check whether your pipeline decodes untrusted IMC or IAC audio files.

## Timeline

- 2026-11-09T19:28:15+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-125073

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-infinite-loop-denial-of-service-via-imc-iac-decoder
- [fix] Patch: github.com https://github.com/FFmpeg/FFmpeg/commit/9b26bb4c9a4457d480899a1bf64ec080eceb1acd

## From the sources

FFmpeg through 9.0.2 contains an infinite loop vulnerability in bit_allocation() in libavcodec/imc.c that allows attackers to hang decoding by supplying audio blocks with a negative bit budget. Attackers can craft IMC or IAC audio files that drive freebits negative, causing the reduction loop to never terminate and consuming 100% CPU.

---

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