What is CVE-2026-42376?

CVE-2026-42376 is a critical-severity vulnerability in D-link Dir-456u Firmware, classified under Use of Hard-coded Credentials. CVSS score: 9.8/10. Published 2026-05-04.

How severe is CVE-2026-42376?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Vulnerability in D-link Dir-456u Firmware

CVE-2026-42376

D-Link DIR-456U Hardware Revision A1 (End-of-Life, EOL) contains a hardcoded telnet backdoor. The device starts a telnet daemon at boot via /etc/init0.d/S80telnetd.sh with the username "Alphanetworks" and the static password "whdrv01_dlob_…

EPSS: 0.002 (38.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

D-link Dir-456u Firmware — versions A1
Dlink Dir-456u — versions a1
Dlink Dir-456u_firmware

Weakness classification (CWE)

CWE-798 — Use of Hard-coded Credentials

References

33c584b5-0579-4c06-b2a0-8d8329fcab9c (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2026-42376?: CVE-2026-42376 is a critical-severity vulnerability in D-link Dir-456u Firmware, classified under Use of Hard-coded Credentials. CVSS score: 9.8/10. Published 2026-05-04.
How severe is CVE-2026-42376?: Critical severity. CVSS v3 base score is 9.8 out of 10.