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Description

D-Link DIR-605L Hardware Revision B2 (End-of-Life, EOL) 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 "wrgn76_dlwbr_dir605L" 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 Reserved 2026-04-27 | Published 2026-05-04 | Updated 2026-05-05 | Assigner securin




CRITICAL: 9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Problem types

CWE-798 Use of Hard-coded Credentials

Product status

Default status
affected

B2 (custom)
affected

Credits

Arjun Basnet from Securin Labs finder

References

www.securin.io/...ackdoor-in-d-link-dir-605l-b2-end-of-life- exploit

www.securin.io/...ackdoor-in-d-link-dir-605l-b2-end-of-life- (D-Link DIR-605L B2 Hardcoded Telnet Backdoor - Securin Advisory)

cve.org (CVE-2026-42373)

nvd.nist.gov (CVE-2026-42373)

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