---
id: "CVE-2026-124031"
page: "https://infrastack.ai/live/CVE-2026-124031"
kind: "vulnerability"
aliases: ["CVE-2026-124031"]
title: "GPAC: crafted XMT file crashes MP4Box through type confusion"
severity: "medium"
cvss: 6.8
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["gpac", "media-processing", "mp4box", "package"]
not_affected_if: ["no-gpac-installed", "trusted-input-only"]
published_at: "2026-11-06T20:17:21+00:00"
first_seen_at: "2026-11-06T20:43:59+00:00"
updated_at: "2026-11-06T20:44:13+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-124031", "first_seen_at": "2026-11-06T20:43:59+00:00"}]
exploit_sources: []
---

# GPAC: crafted XMT file crashes MP4Box through type confusion

Link for people: https://infrastack.ai/live/CVE-2026-124031 (this .md is for agents)

GPAC through 26.07.0 casts a Shape's appearance node to M_Appearance without checking its type. A crafted XMT file can make MP4Box perform an invalid memory read and crash.

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

## How to check

- Run `MP4Box -version` and compare against the fixed release, if the sources name one.
- Check whether your pipeline runs MP4Box or GPAC on XMT files from untrusted sources.

## Timeline

- 2026-11-06T20:43:59+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-124031

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/gpac-through-26.07.0-type-confusion-via-drawable-get-aspect-2d-mpeg4
- [fix] Patch: github.com https://github.com/gpac/gpac/commit/43a8329a90ae2907716b593cc3746458516c7c39

## From the sources

GPAC through 26.07.0 contains a type confusion vulnerability in drawable_get_aspect_2d_mpeg4() and TraverseShape() that casts a Shape's appearance node to M_Appearance without checking its node tag. Attackers can supply a crafted XMT file placing another node type, such as Conditional, in the appearance field to trigger an invalid memory read and crash MP4Box.

---

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