# CVE-2026-91001: D-Link DI-8400 stack buffer overflow in DDNS configuration

Source: https://junglewise.ai/threats/cve-2026-91001-d-link-di-8400-stack-buffer-overflow-in-ddns-configuration  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-15. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-91001 · Severity: critical · CVSS 9.9 · Published 2026-09-15

D-Link DI-8400 is a network appliance with a Dynamic DNS (DDNS) configuration feature that allows remote management of domain names. A remote attacker with network access can trigger a stack-based buffer overflow by sending maliciously crafted DDNS parameters, potentially leading to device crash, data corruption, or arbitrary code execution.

Technologies: [D-Link DI-8400](https://junglewise.ai/threats/technologies/di-8400). Vendors: [D-Link](https://junglewise.ai/threats/vendors/d-link).

## Quick answers

**Is CVE-2026-91001 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-91001 being exploited in the wild.

**How severe is CVE-2026-91001?** Critical severity, with a CVSS score of 9.9, published 15 September 2026.

**Which products and versions are affected?** D-Link DI-8400 16.07.

**Is there a fix for CVE-2026-91001?** 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-2026-91001 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-91001?** Check whether you run D-Link DI-8400 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

The vulnerability is a stack-based buffer overflow in the ddns_asp function within the /ddns.asp component of D-Link DI-8400 firmware version 16.07. The vulnerability exists due to insufficient input validation on DDNS configuration parameters (serv, user, host, wild, mx, bmx, cust, ip). An attacker can send oversized or maliciously crafted input via HTTP POST requests to exceed the buffer boundary and overwrite the stack return address. The attack requires network access to the device's web interface and valid authentication credentials (as evidenced by the cookie-based authentication in exploit code). A public exploit demonstrating the crash has been released. Affected versions: D-Link DI-8400 16.07.

## Affected products

- D-Link DI-8400 16.07

## Timeline

- 2026-09-15: disclosed
- other: Public exploit code released on GitHub

## References

- [https://github.com/Vivi-Xray/Xray-s-cve-/blob/main/ddns_asp/ddns_asp.py](https://github.com/Vivi-Xray/Xray-s-cve-/blob/main/ddns_asp/ddns_asp.py)
- [https://github.com/Vivi-Xray/Xray-s-cve-/tree/main/ddns_asp](https://github.com/Vivi-Xray/Xray-s-cve-/tree/main/ddns_asp)

## Related threats

- [D-Link DI-8400 stack buffer overflow in Web Administration Service](https://junglewise.ai/threats/cve-2026-101081-a-security-flaw-has-been-discovered-in-d-link-di-8400-16-07-this)
- [D-Link DI-8400 stack-based buffer overflow in /dbsrv.asp](https://junglewise.ai/threats/cve-2026-10206-d-link-di-8400-stack-based-buffer-overflow-in-dbsrv-asp)