CVE-2026-42376
Unauthenticated root via hardcoded telnet backdoor on D-Link DIR-456U A1.
Is CVE-2026-42376 being exploited?
Not confirmed. CVE-2026-42376 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.46% probability of exploitation in the next 30 days.
How severe is CVE-2026-42376?
CVE-2026-42376 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-42376?
Not known from our data. No patch reference has been recorded for CVE-2026-42376, which is not the same as no patch existing — a fix may have shipped without a tagged reference, or after this record was written. The vendor advisory is the only authority on whether a fix exists, and mitigations may be available regardless.
What does CVE-2026-42376 affect?
CVE-2026-42376 affects D-Link DIR-456U A1. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-42376?
Replace device; disable telnet/backdoor; segment network.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Attacker on LAN obtains root on the device; full control; no patch due to EOL.
Monitor only
- affectedA1
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.