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

MITRE NVD CVE.ORG JSON API Print: PDF PDF

Summary

CVECVE-2026-42374
StatePUBLISHED
Assignersecurin
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-04 17:16:25 UTC
Updated2026-05-06 12:18:13 UTC
DescriptionD-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.

Risk And Classification

Primary CVSS: v3.1 8.8 HIGH from [email protected]

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

EPSS: 0.000820000 probability, percentile 0.236890000 (date 2026-05-05)

Problem Types: CWE-798 | CWE-798 CWE-798 Use of Hard-coded Credentials

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary8.8HIGHCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.133c584b5-0579-4c06-b2a0-8d8329fcab9cSecondary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNACVSS9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Hardware Dlink Dir-600l b1 All All All
Operating System Dlink Dir-600l Firmware All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA D-Link DIR-600L Firmware affected B1 custom MIPS32 Big-Endian

References

ReferenceSourceLinkTags
www.securin.io/zero-day/cve-2026-42374-hardcoded-telnet-backdoor-in-d-link-d... 134c704f-9b21-4f2e-91b3-4a467353bcc0 www.securin.io Exploit, Third Party Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Arjun Basnet from Securin Labs (en)

Additional Advisory Data

Workarounds

CNA: This product is End-of-Life (EOL) and will NOT receive patches. Users should replace the device. Temporary: connect via backdoor and run "killall telnetd" and "iptables -A INPUT -p tcp --dport 23 -j DROP" (lost on reboot).

© CVE.report 2026 |

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report