---
id: "CVE-2026-128240"
page: "https://infrastack.ai/live/CVE-2026-128240"
kind: "vulnerability"
aliases: ["CVE-2026-128240"]
title: "GPAC: crafted scene file triggers use-after-free and crashes MP4Box"
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-processing", "mp4box", "package"]
not_affected_if: ["gpac-not-installed", "no-untrusted-input"]
published_at: "2026-11-13T10:18:11+00:00"
first_seen_at: "2026-11-13T10:47:33+00:00"
updated_at: "2026-11-13T10:54:55+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-128240", "first_seen_at": "2026-11-13T10:47:33+00:00"}]
exploit_sources: []
---

# GPAC: crafted scene file triggers use-after-free and crashes MP4Box

Link for people: https://infrastack.ai/live/CVE-2026-128240 (this .md is for agents)

GPAC through 26.07.0 frees unregistered prototypes in gf_sg_reset() while scene commands still reference them. A crafted XMT/BT scene file processed by MP4Box -chap can make the process access freed memory and crash.

_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` to see the installed GPAC version and compare it with the fixed release.
- Check whether anything runs `MP4Box -chap` on untrusted XMT or BT files.

## Timeline

- 2026-11-13T10:47:33+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-128240

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/gpac-through-26.07.0-use-after-free-in-gf-sg-proto-del-during-scene-teardown
- [fix] Patch: github.com https://github.com/gpac/gpac/commit/a2e5c62c213b5329a4572fe8e7c333e1ca26d028

## From the sources

GPAC through 26.07.0 contains a use-after-free vulnerability in gf_sg_proto_del() in src/scenegraph/vrml_proto.c because gf_sg_reset() frees unregistered prototypes still referenced by scene commands. Attackers can supply a crafted XMT/BT scene declaring prototypes via commands, processed by MP4Box -chap, to trigger freed memory access and crash the process.

---

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