---
id: "CVE-2026-125226"
page: "https://infrastack.ai/live/CVE-2026-125226"
kind: "vulnerability"
aliases: ["CVE-2026-125226"]
title: "FFmpeg: crafted SBaGen script exhausts memory, causing denial of service"
severity: "medium"
cvss: 6.8
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["ffmpeg", "libavformat", "media-processing", "package"]
not_affected_if: ["no-untrusted-input", "sbagen-decoder-unused"]
published_at: "2026-11-09T19:17:00+00:00"
first_seen_at: "2026-11-09T19:28:19+00:00"
updated_at: "2026-11-09T19:30:31+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-125226", "first_seen_at": "2026-11-09T19:28:19+00:00"}]
exploit_sources: []
---

# FFmpeg: crafted SBaGen script exhausts memory, causing denial of service

Link for people: https://infrastack.ai/live/CVE-2026-125226 (this .md is for agents)

FFmpeg's SBaGen decoder derives an unbounded frame size from the script's sample rate, so a crafted script with a very high sample rate makes it allocate huge audio frames. An attacker can exhaust memory and crash the process.

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

## How to check

- Run `ffmpeg -version` to see whether the installed build is FFmpeg 9.0.2 or earlier.
- Check whether the wavesynth/SBaGen decoder is enabled in the build (unknown from the sources whether it is on by default).

## Timeline

- 2026-11-09T19:28:19+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-125226

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-excessive-memory-allocation-via-sbagen-demuxer
- [fix] Patch: github.com https://github.com/FFmpeg/FFmpeg/commit/1f4b2e22cfba19f94489ec4a17130f4f0d5d8a0c

## From the sources

FFmpeg through 9.0.2 contains an uncontrolled memory allocation vulnerability in sbg_read_header() in libavformat/sbgdec.c that derives an unbounded default frame size from the script's sample rate. Attackers can supply a crafted SBaGen script declaring a very high -r sample rate so the wavesynth decoder allocates enormous audio frames, exhausting memory and causing denial of service.

---

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