# CVE-2026-124561: D-Link DIR-878 stack buffer overflow in HNAP handler

Source: https://junglewise.ai/threats/cve-2026-124561-a-vulnerability-was-determined-in-d-link-dir-878-1-20b05-this  
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-2026-124561 · Severity: high · CVSS 7.5 · Published 2026-11-09

The D-Link DIR-878 wireless router contains a critical flaw in its HNAP handler that allows remote attackers to trigger a stack-based buffer overflow by manipulating VLAN settings. An attacker can exploit this remotely without authentication to crash the router or potentially execute arbitrary code, disrupting network connectivity or compromising the device. This vulnerability affects end-of-life hardware that no longer receives security updates from the vendor.

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-2026-124561 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-124561 being exploited in the wild.

**How severe is CVE-2026-124561?** 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-2026-124561?** 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-2026-124561 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-124561?** 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

The vulnerability is a stack-based buffer overflow in the SetVLANSettings function of prog.cgi in the HNAP Handler component, triggered by manipulation of the VID argument. The flaw allows remote network-based exploitation without prior authentication. An attacker can cause denial of service or potentially achieve code execution on the affected router.

## Affected products

- D-Link DIR-878 1.20B05

## Timeline

- 2026-11-09: disclosed
- 2026-11-09: advisory

## References

- [https://github.com/Zimo-666/DIR-878-cves/tree/main/03-settriggeradic-vlan-stack-overflow](https://github.com/Zimo-666/DIR-878-cves/tree/main/03-settriggeradic-vlan-stack-overflow)
- [https://vuldb.com/cve/CVE-2026-124561](https://vuldb.com/cve/CVE-2026-124561)

## 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 handler](https://junglewise.ai/threats/cve-2026-124563-a-security-flaw-has-been-discovered-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 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)