# CVE-2026-31267: Mercusys MW302R stack buffer overflow in administrative web interface

Source: https://junglewise.ai/threats/cve-2026-31267-mercusys-mw302r-stack-buffer-overflow-in-administrative-web  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-09. Updated: 2026-07-09  
License: CC BY 4.0 with a link back

CVE-2026-31267 · Severity: info · CVSS 4.9 · Published 2026-07-09

The Mercusys MW302R, a wireless router used for home and small office networking, contains a security flaw in its management interface. An authorized administrator can send a specifically formatted request that causes the device to crash or reboot. This results in a total loss of internet connectivity and network services until the device recovers.

Vendors: [Mercusys](https://junglewise.ai/threats/vendors/mercusys).

## Quick answers

**Is CVE-2026-31267 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-31267 being exploited in the wild.

**How severe is CVE-2026-31267?** Informational severity, with a CVSS score of 4.9, published 9 July 2026.

**Which products and versions are affected?** Mercusys MW302R MW302R(EU)_V1_1.4.10 Build 231023 and earlier.

**Is there a fix for CVE-2026-31267?** A patch was published on 2026-04-29: Vendor patch released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-31267 attacked?** It is attacked over the network or from the adjacent network, in a network appliance.

**Am I affected by CVE-2026-31267?** Check whether you run Mercusys MW302R 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 within the administrative web interface of the Mercusys MW302R router. The vulnerability is triggered when the web server processes a specially crafted request, leading to control flow manipulation to an arbitrary instruction address. An attacker must be authenticated with administrative privileges to exploit this flaw. Successful exploitation results in a system crash and subsequent denial of service. The issue is fixed in firmware version MW302R(EU)_V1_1.11.10 Build 260327.

## Affected products

- Mercusys MW302R MW302R(EU)_V1_1.4.10 Build 231023 and earlier

## Timeline

- 2026-04-09: other: CVE reserved
- 2026-04-29: patched: Vendor patch released
- 2026-05-06: disclosed: Public disclosure request submitted
- 2026-07-09: advisory: NVD publication date

## References

- [https://barry-dev.xyz/about](https://barry-dev.xyz/about)
- [https://gist.github.com/BarrYPL/13dcd071673866cbbfaaa05085b98cf3](https://gist.github.com/BarrYPL/13dcd071673866cbbfaaa05085b98cf3)