---
id: "CVE-2026-125240"
page: "https://infrastack.ai/live/CVE-2026-125240"
kind: "vulnerability"
aliases: ["CVE-2026-125240"]
title: "FFmpeg: crafted JPEG XS stream leaks decoder memory until the process exhausts memory"
severity: "medium"
cvss: 6.8
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["ffmpeg", "media-processing", "runtime", "self-hosted", "transcoding"]
not_affected_if: ["no-svt-jpegxs-decoder", "no-untrusted-input"]
published_at: "2026-11-09T19:17:02+00:00"
first_seen_at: "2026-11-09T19:28:20+00:00"
updated_at: "2026-11-09T19:30:24+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-125240", "first_seen_at": "2026-11-09T19:28:20+00:00"}]
exploit_sources: []
---

# FFmpeg: crafted JPEG XS stream leaks decoder memory until the process exhausts memory

Link for people: https://infrastack.ai/live/CVE-2026-125240 (this .md is for agents)

FFmpeg through 9.0.2 leaks decoder instances and buffers in its SVT JPEG XS decoder when frame dimensions are rejected. A crafted JPEG XS stream, for example inside MPEG-TS, can repeatedly trigger the leak and exhaust memory.

_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.
- Check whether FFmpeg was built with SVT JPEG XS support (libsvtjpegxsdec), for example in the output of `ffmpeg -decoders | grep -i jpegxs`.

## Timeline

- 2026-11-09T19:28:20+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-125240

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-resource-leak-in-libsvtjpegxs-jpeg-xs-decoder-wrapper
- [fix] Patch: github.com https://github.com/FFmpeg/FFmpeg/commit/3aa561b0dd2054182fbb9548b4526e8500d52a52

## From the sources

FFmpeg through 9.0.2 contains a resource leak vulnerability in svt_jpegxs_dec_decode() in libsvtjpegxsdec.c that leaks decoder instances when ff_set_dimensions() rejects frame dimensions. Attackers can supply a crafted JPEG XS stream, for example in MPEG-TS, with oversized headers to repeatedly leak decoder threads and buffers, exhausting memory.

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