CVE-2019-20500

What Is the D-Link DWL-2600AP?

The DWL-2600AP is a D-Link enterprise-grade wireless access point marketed for business Wi-Fi deployments, managed through a web-based configuration interface (admin.cgi). Because access points sit at the network edge and often retain administrative credentials for onward management systems, code execution on the device can be a foothold for broader network compromise.

Overview

CVE-2019-20500 is a command injection vulnerability (CWE-78) in the DWL-2600AP's web management interface, specifically in the "Save Configuration" functionality. An authenticated attacker can inject shell metacharacters into the configBackup or downloadServerip parameters of the admin.cgi?action=config_save endpoint, resulting in arbitrary command execution on the device. CVSS 7.8, Attack Vector: Local, reflecting that authentication and some level of access to the management interface is a prerequisite.

Technical Details

The vulnerability occurs because the configuration backup/restore feature builds a shell command using attacker-controllable input (such as a server IP address for downloading/uploading configuration) without properly sanitizing shell metacharacters (e.g. ;, |, backticks). By supplying a crafted value in the downloadServerip or configBackup parameter, an authenticated attacker can append arbitrary OS commands that get executed with the privileges of the web management process — typically root on embedded AP firmware.

Because the flaw requires prior authentication to the admin interface, it is most commonly used as a privilege-escalation or persistence step after an attacker has already obtained (or guessed/brute-forced) valid admin credentials, or in scenarios where default credentials were never changed.

Discovery

D-Link addressed this issue through its standard security advisory process, publishing SAP10113 with remediation guidance.

Exploitation Context

CISA's KEV addition confirms active exploitation of this vulnerability. Enterprise access points with unchanged default credentials or weakly protected admin panels are frequently targeted by botnet operators and opportunistic attackers who chain credential compromise with command injection flaws like this one to gain persistent code execution on network infrastructure.

Remediation

1. Apply the D-Link firmware update referenced in SAP10113, or the latest available firmware for the DWL-2600AP.
2. Change default administrator credentials immediately and enforce strong, unique passwords for device management.
3. Restrict access to the admin web interface to trusted management networks only — never expose it to the internet.
4. Retire end-of-life hardware if the vendor no longer provides security patches for this model.
5. Audit device configuration for unexpected changes to backup/restore server settings that could indicate prior exploitation.