External risk intelligence

D-Link DIR-615 Router WAN Page Accessible Without Authentication

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2021-42627

The vulnerable component is a router administration interface. Such devices are network edge gateways that are often exposed to the internet or accessible via the WAN interface in typical consumer and small-office deployments, making this a public-facing configuration surface by design.

Dlink Dir 615 Firmware

20.06

Halo Surface Signal: 5 out of 5 — more likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A critical vulnerability has been identified in D-Link DIR-615 devices, allowing unauthenticated access to sensitive WAN configuration settings. This could potentially expose network information and permit unauthorized modifications to data fields, impacting the device's security posture.

Unauthenticated access to router settings.
This could expose network details and allow changes.
Confirm relevance and exposure of affected devices.

Attack Path

How an attacker could exploit the issue

An attacker can reach the vulnerable WAN configuration page directly over the network without needing any login credentials. This exposure allows an attacker to view sensitive WAN settings and potentially alter them.

Network access required
Direct access to WAN configuration
Disclosure and modification of WAN settings

Live Threat

Current exploitation, exposure, and threat context

Unauthenticated access to the WAN configuration page could expose sensitive network settings and allow an attacker to modify them, potentially disrupting internet connectivity or facilitating further unauthorized access. This is possible when the affected device is directly accessible from the network.

WAN configuration details could be exposed.
Direct access to the configuration page.
Network disruption or unauthorized access.

Operational Fix

Recommended remediation, mitigation, and detection steps

System and network owners are responsible for managing D-Link DIR-615 devices. The immediate first step is to identify all deployed DIR-615 units, determine their network exposure (especially WAN-side accessibility), and ascertain their business criticality. This will inform prioritization for remediation, which may involve vendor coordination or applying available firmware updates if they mitigate the unauthenticated access vulnerability.

Confirm ownership of all DIR-615 devices.
Verify WAN interface exposure and asset criticality.
Plan for firmware updates or risk mitigation.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

Free EASM Trial See How Signal Works

Frequently asked questions

What is the D-Link DIR-615 router?

The D-Link DIR-615 is a wireless router commonly used in homes and small offices to manage internet connectivity and local network traffic. It acts as a gateway, routing data between your internal devices and the broader internet. The affected firmware version, 20.06, manages the device's internal software controls, including the specialized page used to configure Wide Area Network (WAN) settings that define how the router connects to your internet service provider.

How does CVE-2021-42627 impact security?

This vulnerability is an authentication bypass. It means the security mechanism designed to check for a valid username or password is skipped for the 'wan.htm' page. Because the device fails to require login credentials, an unauthorized person can view sensitive network configuration details or change critical data fields that control how the router communicates with the internet.

When is this router vulnerable to attack?

The vulnerability is triggered when a user or automated agent navigates directly to the 'wan.htm' configuration page without being logged in. The device is not vulnerable if the request is blocked by internal network restrictions or if the management interface is only accessible from a local, trusted network segment, provided the router is not set to allow management access from the WAN side.

Is my D-Link device at risk if it faces the internet?

According to Halo Surface Signal, this vulnerability presents a high risk for devices that are internet-facing. Because this router serves as a network edge gateway, any configuration interface exposed to the public internet can be reached by external attackers. You should consider any device with a publicly accessible WAN interface to be at elevated risk of unauthorized configuration changes.

What steps should I take if I use a DIR-615?

Begin by auditing your network to identify all active DIR-615 units. Determine if the device management interface is accessible from the internet. If you find affected units, prioritize reviewing vendor-provided security bulletins to locate authorized firmware updates that address this authentication issue, or restrict access to the device management page so it is only available from your trusted local network.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.