CVE-2026-36817: Tenda W15E Buffer Overflow DoS Vulnerability

Technical summary

CVE-2026-36817 is a classic buffer overflow (CWE-120) in the formAddWebAuthWhiteUser function of Tenda W15E firmware v15.11.0.10. The vulnerability is triggered via the webAuthWhiteUserInfo parameter in HTTP requests to the web interface. The flaw permits unauthenticated remote exploitation with network-level access, resulting in denial of service through memory corruption and process termination. The CVSS 3.1 score of 7.5 (HIGH) reflects network exploitability with no authentication requirement, though impact is limited to availability.

Business impact

Organizations deploying Tenda W15E routers face risk of network disruption through denial of service attacks. An attacker can remotely crash the device without credentials, forcing manual restart and potential extended downtime for network operations dependent on that access point. This is particularly concerning in SMB or branch office environments where device recovery may not be immediate, affecting business continuity and employee connectivity.

Affected systems

Tenda W15E wireless router firmware version 15.11.0.10 is confirmed vulnerable. Verify against Tenda's official security advisories whether other firmware versions or related Tenda models are affected; the vendor has not provided a comprehensive product scope in available disclosures. Organizations should inventory W15E deployments in production networks and check for available firmware patches.

Exploitability

Exploitation is straightforward and reliable. No authentication is required, no user interaction is needed, and an attacker needs only network access to the device's web interface (typically port 80 or 443). The attack is repeatable and requires only a basic HTTP POST request with a malformed webAuthWhiteUserInfo parameter. The attack surface is broad in any environment where the router is reachable over the network.

Remediation

The primary remediation is to apply a patched firmware version from Tenda. Check Tenda's official security advisory and support portal for version updates addressing CVE-2026-36817. As an interim measure, restrict network access to the router's web management interface using firewall rules or access control lists—limiting HTTP/HTTPS access to trusted administrator networks only will reduce immediate risk until patching is completed.

Patch guidance

Verify the latest available firmware version for Tenda W15E directly from Tenda's official website or support channels. Apply patches in a controlled maintenance window after testing in a non-production environment if possible. Because this vulnerability affects the router's core functionality, ensure you have a recovery plan and documented configuration before upgrading. Confirm patch application by verifying the installed firmware version in the router's web interface or CLI.

Detection guidance

Monitor for HTTP requests containing suspicious or oversized webAuthWhiteUserInfo parameters sent to the router's web interface. Watch for unexpected router restarts or loss of connectivity that correlates with external network activity. Implement network-based intrusion detection signatures for buffer overflow patterns targeting this function if your security infrastructure supports custom rules. Log all access to the router's management interface and review for anomalous requests post-incident.

Why prioritize this

This vulnerability rates HIGH priority due to network accessibility, lack of authentication requirement, and simplicity of exploitation. While impact is limited to denial of service (not confidentiality or integrity compromise), the ease of attack and broad attack surface in network-connected deployments warrant prompt patching. Organizations should schedule remediation within 2-4 weeks depending on business criticality of affected devices.

Risk score, explained

The CVSS 3.1 score of 7.5 reflects a HIGH-severity network-accessible vulnerability requiring no authentication or user interaction. The denial-of-service impact directly affects system availability. The score does not increase to Critical because confidentiality and integrity are not compromised—the attacker can only crash the device, not extract data or modify configurations. However, in environments where network uptime is critical, business risk may exceed the base CVSS score.

Frequently asked questions