NULL Pointer Dereference Vulnerability in GPAC MPEG-4 Form Handlers
CVE-2026-128239

6.8MEDIUM

Key Information:

Vendor

Gpac

Status
Gpac
Vendor
CVE Published:
13 November 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-128239?

GPAC versions up to 26.07.0 contain a vulnerability that allows attackers to exploit NULL pointer dereference in the MPEG-4 Form spatial-constraint handlers. This occurs when an attacker provides a crafted XMT scene with Form constraints that reference a nonexistent group, which can lead to process crashes and potential denial of service, particularly evident when importing chapters in tools like MP4Box.

Affected Version(s)

gpac 0 <= 26.07.0

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-128239 - Proof of Concept

References

https://github.com/gpac/gpac/issues/4029
issue-tracking
https://github.com/gpac/gpac/commit/bc416b997622e43de65af...
patch
https://github.com/gpac/gpac/blob/v26.07.0/src/compositor...
technical-description

CVSS V4

Score:
6.8
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Local
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

Alexander A. Shvedov (sigdevel)
Jean Le Feuvre
.