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Vulnerability details

CVE-2026-42374

D-Link DIR-600L Firmware

D-Link DIR-600L B1 Hardcoded Telnet Backdoor Credentials

CVSS 3.1
9.8Critical

Official description

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 "wrgn61_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.

CVSS scores

ScoreVersionSourceVector
9.8Critical 3.1 CVEProject cvelistV5 (CNA) (securin) CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

VendorProductVersionsSource
D-Link DIR-600L Firmware B1 CVEProject cvelistV5 (CNA)

References and advisories

1
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Details

Published
2026-05-04
Last updated
2026-05-05
State
Published
Assigner (CNA)
securin

Exploit prediction (EPSS)

0.47%
Probability of exploitation in 30 days
41.1%
Percentile (among all CVEs)

SSVC assessment (CISA)

Automatable
No
Exploitation
Proof of concept
Technical impact
Total

Weaknesses (CWE)

  • CWE-798
    Use of Hard-coded Credentials