CVE-2026-42375Public exploit

Root shell access via hardcoded Telnet credentials

Published May 4, 2026 · Updated May 4, 2026

Hardcoded credentials in D-Link DIR-600L Firmware A1 allow remote attackers to obtain a root shell through the boot-time Telnet service. /bin/telnetd.sh unconditionally starts telnetd with the fixed Alphanetworks username and a plaintext password read from /etc/alpha_config/image_sign. Access from the same LAN or Wi-Fi network is required, and successful authentication grants full administrative control of the router.

CVSS severity8.8
High
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Hardcoded credentials in D-Link DIR-600L Firmware A1 allow remote attackers to obtain a root shell through the boot-time Telnet service. /bin/telnetd.sh unconditionally starts telnetd with the fixed Alphanetworks username and a plaintext password read from /etc/alpha_config/image_sign. Access from the same LAN or Wi-Fi network is required, and successful authentication grants full administrative control of the router.

The record

CVE
CVE-2026-42375
Published
May 4, 2026
Updated
May 4, 2026
Vendor
D-Link
Product
DIR-600L Firmware
Classifications
CWE-798, T1078.001
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 4, 2026CVE publishedPublication date reported by the CVE source.
  2. May 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=A1

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

D-Link · DIR-600L Firmwareversion=A1

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8SecurinCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-798Use of Hard-coded Credentials
T1078.001Valid Accounts: Default Accounts

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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