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CVE-2026-42373

D-Link DIR-605L B2 Hardcoded Telnet Backdoor Credentials

Published: May 4, 2026Updated: May 6, 2026 Sources: CVE List NVD BDUCWE-798
NVD MITRE
9.8CVSSCRITICAL
EPSS Score
0.5%
Top 62.9%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:HI:HA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High
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Weaknesses

CWE-798

Affected Products

DIR-605L FirmwareD-LinkNetworking Infrastructure
dir-605l firmwaredlinkNetworking Infrastructure
DIR-605LD-Link Corp.Networking Infrastructure
d-linkcommercialTWNetworking Infrastructure
dlinkcommercialTWNetworking Infrastructure
d-link corp.commercialTWNetworking Infrastructureaka d-link corporation, d-link international

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available
Workaround Available

MITRE ATT&CK

2 techniques
Credential Access
Initial Access
View detailed technique mapping

References

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

Timeline

Published
May 4, 2026
Last Updated
May 6, 2026

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