Is CVE-2025-55640 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2025-55640 being exploited in the wild.

How severe is CVE-2025-55640?

Informational severity, published 16 October 2026.

Is there a fix for CVE-2025-55640?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2025-55640 attacked?

It is attacked with local access or over the network, in a software library.

Am I affected by CVE-2025-55640?

Check whether you run Gpac MP4Box at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2025-55640: GPAC MP4Box heap buffer overflow in stbl_AddSize

CVE-2025-55640 · Severity: info · Published 2026-10-16

GPAC MP4Box is a command-line tool for encoding and manipulating MP4 media files. A heap buffer overflow flaw in the stbl_AddSize function allows an attacker to crash the application by supplying a crafted MP4 file, resulting in denial of service. Users who process untrusted media files with MP4Box are at risk of application disruption.

Technologies: Gpac MP4Box. Vendors: Gpac.

Quick answers

Is CVE-2025-55640 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2025-55640 being exploited in the wild.
How severe is CVE-2025-55640?: Informational severity, published 16 October 2026.
Which products and versions are affected?: Gpac MP4Box v2.4.
Is there a fix for CVE-2025-55640?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2025-55640 attacked?: It is attacked with local access or over the network, in a software library.
Am I affected by CVE-2025-55640?: Check whether you run Gpac MP4Box at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A heap buffer overflow exists in the stbl_AddSize function within isomedia/stbl_write.c of GPAC MP4Box v2.4. The vulnerability is triggered when processing a specially crafted MP4 file that causes incorrect size tracking in the sample size box. The attack requires no authentication and is delivered via a malicious file; a local attacker or remote attacker supplying a file can trigger a denial of service condition.

Affected products

GPAC MP4Box v2.4

Timeline

2025-10-16: disclosed

References

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