# CVE-2025-55643: GPAC MP4Box NULL pointer dereference in TrackWriter

Source: https://junglewise.ai/threats/cve-2025-55643-gpac-mp4box-null-pointer-dereference-in-trackwriter  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-15. Updated: 2026-06-15  
License: CC BY 4.0 with a link back

CVE-2025-55643 · Severity: info · CVSS 5.5 · Published 2026-06-15

A vulnerability in the GPAC MP4Box utility, a tool used for processing and packaging multimedia files, can lead to a sudden application crash. By tricking a user into processing a specially crafted MP4 file, an attacker can cause the software to stop functioning. This results in a denial of service, potentially disrupting automated media processing workflows or individual user tasks.

Technologies: [Gpac MP4Box](https://junglewise.ai/threats/technologies/mp4box). Vendors: [Gpac](https://junglewise.ai/threats/vendors/gpac).

## Quick answers

**Is CVE-2025-55643 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-55643 being exploited in the wild.

**How severe is CVE-2025-55643?** Informational severity, with a CVSS score of 5.5, published 15 June 2026.

**Which products and versions are affected?** Gpac MP4Box 2.4.

**Is there a fix for CVE-2025-55643?** 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-2025-55643 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2025-55643?** 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 NULL pointer dereference exists in the TrackWriter handling component within filters/mux_isom.c of GPAC MP4Box v2.4. The vulnerability is triggered when the application attempts to process a maliciously crafted MP4 file that lacks expected data structures, leading to an invalid memory access. An attacker can exploit this by providing a specially designed file to be processed by the utility, resulting in an immediate crash (Denial of Service). This is a local attack vector requiring the user or an automated system to open the malicious file. No information regarding a formal patch was provided in the advisory.

## Affected products

- GPAC MP4Box 2.4

## Timeline

- 2026-06-15: disclosed: Initial disclosure of the vulnerability
- 2026-06-15: advisory: NVD record published

## References

- [https://infosec.exchange/@sigdevel/116736819671963019](https://infosec.exchange/@sigdevel/116736819671963019)

## Related threats

- [GPAC MP4Box segmentation fault in dump_isom_saps](https://junglewise.ai/threats/cve-2025-55667-a-segmentation-violation-in-the-dump-isom-saps-function-mp4box)
- [GPAC MP4Box use-after-free in gf_filter_pid_get_packet](https://junglewise.ai/threats/cve-2025-55654-a-use-after-free-in-the-gf-filter-pid-get-packet-function-filter)
- [GPAC MP4Box floating point exception in gf_parse_lfrac](https://junglewise.ai/threats/cve-2025-55653-gpac-mp4box-v2-4-was-discovered-to-contain-a-floating-point)
- [GPAC MP4Box heap buffer overflow in stbl_AddSize](https://junglewise.ai/threats/cve-2025-55640-a-heap-buffer-overflow-in-the-stbl-addsize-function-isomedia-stbl)
- [GPAC MP4Box use-after-free in gf_node_deactivate_ex](https://junglewise.ai/threats/cve-2026-90827-gpac-mp4box-use-after-free-in-gf-node-deactivate-ex)