How severe is CVE-2026-42375?

CVE-2026-42375 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-42375 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (38th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-42375?

CVE-2026-42375 affects Dlink Dir-600l Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-42375?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-42375 have an EU (EUVD) identifier?

Yes. CVE-2026-42375 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27027.

When was CVE-2026-42375 published?

CVE-2026-42375 was published on 2026-05-04 and last updated on 2026-06-17.

CVE-2026-42375

CVE-2026-42375 is a critical-severity vulnerability in Dlink Dir-600l Firmware with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-798.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 0% (38th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-27027
Weakness: CWE-798
Affected product: Dlink Dir-600l Firmware
Published: 2026-05-04
Last modified: 2026-06-17

Description

D-Link DIR-600L Hardware Revision A1 (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 "wrgn35_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.

Frequently asked questions

What is CVE-2026-42375?: D-Link DIR-600L Hardware Revision A1 (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 "wrgn35_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.
How severe is CVE-2026-42375?: CVE-2026-42375 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-42375 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (38th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-42375?: CVE-2026-42375 affects Dlink Dir-600l Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-42375?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-42375 have an EU (EUVD) identifier?: Yes. CVE-2026-42375 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27027.
When was CVE-2026-42375 published?: CVE-2026-42375 was published on 2026-05-04 and last updated on 2026-06-17.

References

https://www.securin.io/zero-day/cve-2026-42375-hardcoded-telnet-backdoor-in-d-link-dir-600l-a1-end-of-life-

Affected products (1)

cpe:2.3:o:dlink:dir-600l_firmware:*:*:*:*:*:*:*:*

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