CVE-2026-42374: D-Link DIR-600L B1 Hardcoded Telnet Backdoor Credentials
D-Link DIR-600L Hardware Revision B1 (End-of-Life) contains a hardcoded telnet backdoor. The device starts a telnet daemon at boot via /bin/telnetd.sh with the username "Alphanetworks" and the static password "wrgn61dlwbrdir600L" read from /etc/alphaconfig/imagesign. The custom telnetd binary accepts a -u user:password flag, and the custom login binary uses strcmp() to validate credentials. Successful authentication grants an unauthenticated attacker on the local network a root shell with full administrative control. The device has reached End-of-Life (EOL) and will not receive patches.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-42374?
CVE-2026-42374 is classified as a high severity vulnerability due to the presence of hardcoded telnet backdoor credentials.
How do I fix CVE-2026-42374?
The best way to remediate CVE-2026-42374 is to discontinue use of the affected D-Link DIR-600L B1 device and replace it with a more secure model.
What are the risks associated with CVE-2026-42374?
The risks include unauthorized access to the device, potential data breaches, and compromise of the local network due to the hardcoded backdoor.
Which devices are affected by CVE-2026-42374?
CVE-2026-42374 affects the D-Link DIR-600L Hardware Revision B1 model specifically.
Is D-Link planning to address CVE-2026-42374?
As the D-Link DIR-600L B1 is listed as an end-of-life device, no official fix or update is expected to address CVE-2026-42374.