# CVE-2025-55639: GPAC MP4Box NULL pointer dereference in gf_isom_add_track_kind

Source: https://junglewise.ai/threats/cve-2025-55639-gpac-mp4box-null-pointer-dereference-in-gf-isom-add-track-kind  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-23. Updated: 2026-06-23  
License: CC BY 4.0 with a link back

CVE-2025-55639 · Severity: info · CVSS 5.5 · Published 2026-06-23

GPAC MP4Box, a popular tool for processing multimedia files, contains a vulnerability that can cause the application to crash. By tricking a user into opening a specially crafted MP4 file, an attacker can trigger a denial-of-service condition. This could disrupt workflows or automated systems that rely on MP4Box for media processing.

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

## Quick answers

**Is CVE-2025-55639 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-55639 being exploited in the wild.

**How severe is CVE-2025-55639?** Informational severity, with a CVSS score of 5.5, published 23 June 2026.

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

**Is there a fix for CVE-2025-55639?** A patch was published on 2025-06-18: Fix committed to GPAC repository Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2025-55639 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2025-55639?** 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 GPAC MP4Box v2.4 within the gf_isom_add_track_kind() function located in isomedia/isom_write.c. The vulnerability is triggered when the function attempts to process a 'kind' parameter using gf_strdup() without first verifying if the pointer is NULL, specifically when handling crafted MP4 files containing MPEG-H Audio tracks. An attacker can exploit this by providing a malicious MP4 file, leading to a segmentation fault and application crash (Denial of Service). A fix has been committed to the GPAC repository which adds a null guard before the string duplication call.

## Affected products

- GPAC MP4Box 2.4

## Timeline

- 2025-06-18: disclosed: Issue reported on GitHub
- 2026-06-23: advisory: CVE published to NVD
- 2025-06-18: patched: Fix committed to GPAC repository

## References

- [https://github.com/gpac/gpac/commit/027ce139dda498ee95df36db9f9f6f3cadce8ec9](https://github.com/gpac/gpac/commit/027ce139dda498ee95df36db9f9f6f3cadce8ec9)
- [https://github.com/gpac/gpac/issues/3260](https://github.com/gpac/gpac/issues/3260)
- [https://github.com/sigdevel/pocs/blob/main/res/gpac/MP4Box/23/23_poc.mp4](https://github.com/sigdevel/pocs/blob/main/res/gpac/MP4Box/23/23_poc.mp4)
- [https://infosec.exchange/@sigdevel/116769184815236865](https://infosec.exchange/@sigdevel/116769184815236865)

## 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)