# CVE-2026-124563: D-Link DIR-878 buffer overflow in HNAP SetWanSettings handler

Source: https://junglewise.ai/threats/cve-2026-124563-a-security-flaw-has-been-discovered-in-d-link-dir-878-1-20b05  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-09. Updated: 2026-11-09  
License: CC BY 4.0 with a link back

CVE-2026-124563 · Severity: high · CVSS 7.5 · Published 2026-11-09

D-Link DIR-878 is a wireless router used in home and small office networks. A buffer overflow flaw in its web-based configuration interface allows a remote attacker to execute arbitrary code and potentially take complete control of the device. The vulnerability affects unsupported versions of the firmware and poses a significant risk to network security.

Technologies: [D-Link DIR-878](https://junglewise.ai/threats/technologies/d-link-dir-878). Vendors: [D-Link](https://junglewise.ai/threats/vendors/d-link).

## Quick answers

**Is CVE-2026-124563 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-124563 being exploited in the wild.

**How severe is CVE-2026-124563?** High severity, with a CVSS score of 7.5, published 9 November 2026.

**Which products and versions are affected?** D-Link DIR-878 1.20B05.

**Is there a fix for CVE-2026-124563?** 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-2026-124563 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-124563?** Check whether you run D-Link DIR-878 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 stack-based buffer overflow exists in the HNAP Handler's SetWanSettings function when processing Primary/Secondary DNS arguments. The vulnerability can be exploited remotely without authentication to achieve arbitrary code execution on the router. While no active exploitation in the wild has been reported, proof-of-concept code has been publicly released, increasing exploitation risk.

## Affected products

- D-Link DIR-878 1.20B05

## Timeline

- 2026-11-09: disclosed

## References

- [https://github.com/Zimo-666/DIR-878-cves/tree/main/05-setwansettings-l2tp-pptp-dns-overflow](https://github.com/Zimo-666/DIR-878-cves/tree/main/05-setwansettings-l2tp-pptp-dns-overflow)
- [https://vuldb.com/cve/CVE-2026-124563](https://vuldb.com/cve/CVE-2026-124563)

## Related threats

- [D-Link DIR-878 path traversal in HNAP handler](https://junglewise.ai/threats/cve-2026-124564-a-weakness-has-been-identified-in-d-link-dir-878-1-20b05)
- [D-Link DIR-878 buffer overflow in HNAP SetWanSettings](https://junglewise.ai/threats/cve-2026-124562-a-vulnerability-was-identified-in-d-link-dir-878-1-20b05)
- [D-Link DIR-878 stack buffer overflow in HNAP handler](https://junglewise.ai/threats/cve-2026-124561-a-vulnerability-was-determined-in-d-link-dir-878-1-20b05-this)
- [D-Link DIR-878 heap buffer overflow in HNAP Handler](https://junglewise.ai/threats/cve-2026-124560-a-vulnerability-was-found-in-d-link-dir-878-1-20b05-this-affects)