---
id: "CVE-2026-125182"
page: "https://infrastack.ai/live/CVE-2026-125182"
kind: "vulnerability"
aliases: ["CVE-2026-125182"]
title: "FFmpeg: crafted RealMedia file leaks memory through Cook audio decoder"
severity: "medium"
cvss: 4.8
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["ffmpeg", "media-processing", "package", "realmedia"]
not_affected_if: ["no-realmedia-decoding", "trusted-input-only"]
published_at: "2026-11-09T19:16:53+00:00"
first_seen_at: "2026-11-09T19:28:17+00:00"
updated_at: "2026-11-09T19:32:21+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-125182", "first_seen_at": "2026-11-09T19:28:17+00:00"}]
exploit_sources: []
---

# FFmpeg: crafted RealMedia file leaks memory through Cook audio decoder

Link for people: https://infrastack.ai/live/CVE-2026-125182 (this .md is for agents)

FFmpeg through 9.0.2 fails to validate a Cook decoder field, so a crafted RealMedia file can read past a buffer. The read leaks pointers and decoder state into decoded audio, which can help an attacker defeat address randomization.

_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`; versions through `9.0.2` are in the affected range.
- Find where FFmpeg is used to decode RealMedia (`.rm`, `.ra`) files from untrusted sources, such as upload or transcoding pipelines.

## Fix

- FFmpeg: a patch is linked from the advisory sources; the fixed version is unknown from the sources.

## Timeline

- 2026-11-09T19:28:17+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-125182

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-out-of-bounds-read-via-cook-decoder-js-subband-start
- [fix] Patch: github.com https://github.com/FFmpeg/FFmpeg/commit/7145d13201c9f9c5253f40295714faa4f4ada1a0

## From the sources

FFmpeg through 9.0.2 contains an out-of-bounds read vulnerability in the Cook decoder joint_decode() function because cook_decode_init() does not check js_subband_start against subbands. Attackers can supply a crafted RealMedia file whose extradata causes reads past decode_buffer_0, leaking pointers and decoder state into decoded audio to help defeat ASLR.

---

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