CRITICAL: CVE-2026-42373 (CVSS 9.8) — multiple products

CVE: CVE-2026-42373

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

Severity: CRITICAL

Status: Critical advisory

Affected

_See vendor advisory_

Summary

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.

Verified Sources

• NVD entry
• GitHub Advisory
• MITRE

References

• https://www.securin.io/zero-day/cve-2026-42373-hardcoded-telnet-backdoor-in-d-link-dir-605l-b2-end-of-life-
• https://www.securin.io/zero-day/cve-2026-42373-hardcoded-telnet-backdoor-in-d-link-dir-605l-b2-end-of-life-

_Validated by the Lyrie Threat Intelligence Pipeline — 3 independent sources confirmed before publication. No speculation._