---
id: "CVE-2026-124030"
page: "https://infrastack.ai/live/CVE-2026-124030"
kind: "vulnerability"
aliases: ["CVE-2026-124030"]
title: "GPAC: crafted XMT file crashes MP4Box via 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-untrusted-xmt-input"]
published_at: "2026-11-06T20:17:21+00:00"
first_seen_at: "2026-11-06T20:43:59+00:00"
updated_at: "2026-11-06T20:44:14+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-124030", "first_seen_at": "2026-11-06T20:43:59+00:00"}]
exploit_sources: []
---

# GPAC: crafted XMT file crashes MP4Box via type confusion

Link for people: https://infrastack.ai/live/CVE-2026-124030 (this .md is for agents)

GPAC through 26.07.0 fails to check BIFS field-replace command types in gf_sg_command_apply(), so a crafted XMT file causes a type confusion. Opening the file in MP4Box, for example through chapter import, makes the tool memcpy from invalid pointers and crash.

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

## How to check

- Check the installed GPAC version with `MP4Box -version` and compare it against the affected range through 26.07.0.

## Timeline

- 2026-11-06T20:43:59+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-124030

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/gpac-through-26.07.0-type-confusion-via-gf-sg-command-apply-xmt-field-replace
- [fix] Patch: github.com https://github.com/gpac/gpac/commit/1359c4da9329cedceeb8fcfeab6d97e0927236e1

## From the sources

GPAC through 26.07.0 contains a type confusion vulnerability in gf_sg_command_apply() in src/scenegraph/commands.c that fails to verify BIFS field-replace command types match target node fields. Attackers can supply a crafted XMT file opened with MP4Box, such as via chapter import, causing gf_sg_vrml_field_clone() to memcpy from invalid pointers and crash.

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