# CVE-2026-36909: Aleksoid1978 MPC-BE NULL pointer dereference in AP4_TkhdAtom::GetTrackId

Source: https://junglewise.ai/threats/cve-2026-36909-aleksoid1978-mpc-be-null-pointer-dereference-in-ap4-tkhdatom  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-01. Updated: 2026-07-01  
License: CC BY 4.0 with a link back

CVE-2026-36909 · Severity: info · CVSS 5.5 · Published 2026-07-01

MPC-BE is a popular open-source media player for Windows. A vulnerability was found where opening a specially crafted MP4 video file can cause the application to crash or stop responding. This issue primarily affects the reliability of the software and could be used to disrupt a user's ability to play media files.

Technologies: [Aleksoid1978 MPC-BE](https://junglewise.ai/threats/technologies/mpc-be). Vendors: [Aleksoid1978](https://junglewise.ai/threats/vendors/aleksoid1978).

## Quick answers

**Is CVE-2026-36909 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-36909 being exploited in the wild.

**How severe is CVE-2026-36909?** Informational severity, with a CVSS score of 5.5, published 1 July 2026.

**Which products and versions are affected?** Aleksoid1978 MPC-BE before commit 4341cb3.

**Is there a fix for CVE-2026-36909?** 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-2026-36909 attacked?** It is attacked with local access, in a network appliance.

**Am I affected by CVE-2026-36909?** Check whether you run Aleksoid1978 MPC-BE 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 AP4_TkhdAtom::GetTrackId() function within the Bento4 library component used by Aleksoid1978 MPC-BE. The vulnerability is triggered when the application attempts to parse a malformed MP4 file containing specific atom structures. An attacker can exploit this by providing a crafted file to a user, which, when opened, causes the media player to crash (Denial of Service). The issue was addressed in commit 4341cb3.

## Affected products

- Aleksoid1978 MPC-BE before commit 4341cb3

## Timeline

- 2026-07-01: advisory: NVD publication date
- 2026-07-01: disclosed

## References

- [https://github.com/Aleksoid1978/MPC-BE/issues/1062](https://github.com/Aleksoid1978/MPC-BE/issues/1062)
- [https://github.com/axiomatic-systems/Bento4/issues/965](https://github.com/axiomatic-systems/Bento4/issues/965)

## Related threats

- [Aleksoid1978 MPC-BE NULL pointer dereference in AP4_AtomSampleTable](https://junglewise.ai/threats/cve-2026-36912-aleksoid1978-mpc-be-null-pointer-dereference-in-ap4)
- [Aleksoid1978 MPC-BE division by zero in CStreamSwitcherOutputPin](https://junglewise.ai/threats/cve-2026-36911-aleksoid1978-mpc-be-division-by-zero-in-cstreamswitcheroutputpin)
- [Aleksoid1978 MPC-BE access violation in BaseSplitterFile::Read](https://junglewise.ai/threats/cve-2026-36910-aleksoid1978-mpc-be-access-violation-in-basesplitterfile-read)