{"id":"CVE-2026-42375","aliases":["EUVD-2026-27027","GHSA-rgp4-f9jj-fjwc"],"status":"published","title":"D-Link DIR-600L A1 Hardcoded Telnet Backdoor Credentials","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.","severity":{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00472,"percentile":0.41169,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-798"],"published":"2026-05-04T16:02:17Z","modified":"2026-10-26T19:10:00Z","products":[{"vendor":"d-link","product":"dir-600l firmware"},{"vendor":"dlink","product":"dir-600l_firmware"}],"references":[{"url":"https://www.securin.io/zero-day/cve-2026-42375-hardcoded-telnet-backdoor-in-d-link-dir-600l-a1-end-of-life-","tags":["exploit","Exploit","Third Party Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42375"},{"url":"https://github.com/advisories/GHSA-rgp4-f9jj-fjwc"}],"sources":{"cve":[{"id":"CVE-2026-42375","title":"D-Link DIR-600L A1 Hardcoded Telnet Backdoor Credentials","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.","status":"published","published":"2026-05-04T16:02:17.044Z","modified":"2026-05-05T12:43:07.508Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"cna"}],"cwes":["CWE-798"],"updated_at":"2026-11-02T13:40:23.731501Z"}],"euvd":[{"id":"EUVD-2026-27027","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.","status":"published","published":"2026-05-04T16:02:17Z","modified":"2026-05-05T12:43:07Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T19:05:17.068199Z"}],"ghsa":[{"id":"GHSA-rgp4-f9jj-fjwc","title":"D-Link DIR-600L Hardware Revision A1 (End-of-Life) contains a hardcoded telnet backdoor. The...","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.","status":"published","published":"2026-05-04T18:30:31Z","modified":"2026-05-04T18:30:42Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-798"],"updated_at":"2026-11-02T15:07:54.172768Z"}],"nvd":[{"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.","status":"published","published":"2026-05-04T17:16:25.847Z","modified":"2026-10-26T19:10:00.163Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"secondary"},{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"high","assessor":"primary"}],"cwes":["CWE-798"],"updated_at":"2026-11-02T14:12:17.022502Z"}]}}