---
id: "CVE-2026-120243"
kind: "vulnerability"
aliases: ["CVE-2026-120243"]
title: "FFmpeg: crafted Go2Meeting video stream leaks stack memory into output"
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: ["trusted-input-only", "versions-outside-range"]
published_at: "2026-11-01T01:17:17+00:00"
first_seen_at: "2026-11-01T01:47:20+00:00"
updated_at: "2026-11-01T01:47:43+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-120243", "first_seen_at": "2026-11-01T01:47:20+00:00"}]
---

# FFmpeg: crafted Go2Meeting video stream leaks stack memory into output

FFmpeg versions 2.0 through 9.0.2 read uninitialized stack memory when decoding a crafted G2M3 or G2M4 (Go2Meeting) video stream with a short palette. An attacker can get stack contents, including pointers or stack guards, copied into the decoded output.

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

## How to check

- Run `ffmpeg -version` and compare against the affected range `2.0` through `9.0.2`.
- Check whether your pipeline decodes untrusted Go2Meeting (G2M) video files.

## Timeline

- 2026-11-01T01:47:20+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-120243

## From the sources

FFmpeg 2.0 through 9.0.2 contains a use of uninitialized variable vulnerability in the Go2Meeting decoder that allows attackers to leak stack memory through out-of-range palette indices. Attackers can craft a G2M3/G2M4 stream with a short Kempf palette so kempf_restore_buf() copies uninitialized stack bytes, including pointers or stack guards, into decoded output.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_