---
id: "CVE-2026-128239"
page: "https://infrastack.ai/live/CVE-2026-128239"
kind: "vulnerability"
aliases: ["CVE-2026-128239"]
title: "GPAC: crafted scene file crashes MP4Box with a NULL pointer"
severity: "medium"
cvss: 6.8
epss: null
exploited: false
status: "open"
category: "package"
products: [{"name": "GPAC", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["gpac", "media-pipelines", "mp4box", "package"]
not_affected_if: ["no-untrusted-xmt-input"]
published_at: "2026-11-13T10:18:11+00:00"
first_seen_at: "2026-11-13T10:47:33+00:00"
updated_at: "2026-11-13T10:54:56+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-128239", "first_seen_at": "2026-11-13T10:47:33+00:00"}]
exploit_sources: []
---

# GPAC: crafted scene file crashes MP4Box with a NULL pointer

Link for people: https://infrastack.ai/live/CVE-2026-128239 (this .md is for agents)

GPAC, a multimedia framework, has a NULL pointer dereference in its MPEG-4 Form constraint handling. A crafted XMT scene file that references a missing group makes the process crash, which is a denial of service.

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

## Affected

- vendor:GPAC affected range not listed fixed no fixed version listed

## How to check

- Run `MP4Box -version` or `gpac -version` to see the installed GPAC version
- Check whether tools that import untrusted XMT scene files, such as MP4Box chapter import, are used on your systems

## Fix

- GPAC: move to a release later than `26.07.0`; the sources do not name the fixed version

## Timeline

- 2026-11-13T10:47:33+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-128239

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/gpac-through-26.07.0-null-pointer-dereference-via-mpeg-4-form-handlers
- [fix] Patch: github.com https://github.com/gpac/gpac/commit/bc416b997622e43de65afab3bae9b7d05d72f2b0

## From the sources

GPAC through 26.07.0 contains a NULL pointer dereference vulnerability in the MPEG-4 Form spatial-constraint handlers in src/compositor/mpeg4_form.c that lets attackers crash the process via unchecked group lookups. Attackers can supply a crafted XMT scene whose Form constraints reference a non-existent group, crashing tools like MP4Box during chapter import for denial of service.

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