D-Link DIR-605L A1 Hardcoded Telnet Backdoor Credentials

published 2026-05-04 6 mo ago modified 2026-10-26 13 d ago also EUVD-2026-27021

cvss: 8.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 22%
public exploits: 0; none known

D-Link DIR-605L Hardware Revision A1 (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 "wrgn35_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.

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: total
Assessed: 6 mo ago (2026-05-04)

Exploit prediction

0.30% chance of exploitation in the next 30 days, higher than 22% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

securin.io https://www.securin.io/zero-day/cve-2026-42372-hardcoded-telnet-backdoor-in-d-link-dir-605l-a1-end-of-life- referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	8.8	CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

D-Link DIR-605L Firmware

Classification

Weakness

CWE-798 Use of Hard-coded Credentials

References

securin.io /zero-day/cve-2026-42372-hardcoded-telnet-backdoor-in-d-link-dir-605l-a1-end-of-life-
exploit, third-party-advisory

Sources

CVE List CVE-2026-42372
NVD CVE-2026-42372

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary