{"identifier":"CVE-2026-42375","cve":{"id":"CVE-2026-42375","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.","published":"2026-05-04T17:16:25.847000+00:00","modified":"2026-10-26T19:10:00.163000+00:00","status":"Analyzed","score":9.8,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvss_version":"3.1","affected":[{"criteria":"cpe:2.3:o:dlink:dir-600l_firmware:*:*:*:*:*:*:*:*","versionStartIncluding":"","versionStartExcluding":"","versionEndIncluding":"","versionEndExcluding":""}],"weaknesses":["CWE-798"],"references":[{"url":"https://www.securin.io/zero-day/cve-2026-42375-hardcoded-telnet-backdoor-in-d-link-dir-600l-a1-end-of-life-","source":"33c584b5-0579-4c06-b2a0-8d8329fcab9c","tags":["Exploit","Third Party Advisory"]},{"url":"https://www.securin.io/zero-day/cve-2026-42375-hardcoded-telnet-backdoor-in-d-link-dir-600l-a1-end-of-life-","source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","tags":["Exploit","Third Party Advisory"]}],"kev":null,"kev_checked":true,"metrics":{"cvssMetricV31":[{"source":"33c584b5-0579-4c06-b2a0-8d8329fcab9c","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":5.9},{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":8.8,"baseSeverity":"HIGH","attackVector":"ADJACENT_NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":2.8,"impactScore":5.9}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-05-05T03:56:21.727703Z","id":"CVE-2026-42375","options":[{"exploitation":"poc"},{"automatable":"no"},{"technicalImpact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[{"operator":"AND","nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:dlink:dir-600l_firmware:*:*:*:*:*:*:*:*","matchCriteriaId":"585AD6F9-C845-430D-B77B-7463872EAD98"}]},{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":false,"criteria":"cpe:2.3:h:dlink:dir-600l:a1:*:*:*:*:*:*:*","matchCriteriaId":"F75E7D9C-03BE-4301-AF9E-9929C33F4EEA"}]}]}],"source":"nvd","retrieved_at":"2026-10-28T10:19:57.789057+00:00","exploited":false,"kev_stale":false,"products":["dlink / dir-600l firmware"],"priority":{"label":"Critical technical severity","reasons":["CVSS is at least 9.0; exploitation is not established by severity alone."]},"epss":{"probability":0.00472,"percentile":0.40681,"date":"2026-10-27","stale":false},"version_assessment":null},"news":[],"campaigns":[],"domains":[{"domain":"www.securin.io","source_url":"https://www.securin.io/zero-day/cve-2026-42375-hardcoded-telnet-backdoor-in-d-link-dir-600l-a1-end-of-life-","investigate_url":"https://investigate.aeglixmind.com/#www.securin.io"}],"arsenal_url":"https://arsenal.aeglixmind.com/?cve=CVE-2026-42375","catalog_url":"https://cves.aeglixmind.com/cve/CVE-2026-42375","research_url":"https://investigate.aeglixmind.com/research/cve/CVE-2026-42375","coverage":{"news_candidates_checked":0,"campaign_candidates_checked":0,"bounded":false,"notice":"Exact CVE mentions in stored public excerpts and reviewed campaign content only. A mention is not proof of exploitation, attribution or tool suitability. Missing matches do not establish absence."}}