Vulnerability in D-Link Dir-600l Firmware

CVE-2026-42375

D-Link DIR-600L Hardware Revision A1 (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 "wrgn35_dlwbr_dir600l" read from /etc/alpha_config/image_sign. 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.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.010 (60.6th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 61st percentile — 60.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-42375: rose from 0.005 to 0.010.

EPSS over last 30 days · oldest: 0.005 · newest: 0.010 · change: +0.005

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-42375?
CVE-2026-42375 is a critical-severity vulnerability in D-Link Dir-600l Firmware, classified under Use of Hard-coded Credentials. CVSS score: 9.8/10. Published 2026-05-04.
How severe is CVE-2026-42375?
Critical severity. CVSS v3 base score is 9.8 out of 10.