CVE-2026-4205: D-Link Dnr-202l Firmware

Critical severity, CVSS 9.8. EPSS: 5.1% chance of exploitation in the next 30 days.

A vulnerability has been found in D-Link DNS-120, DNR-202L, DNS-315L, DNS-320, DNS-320L, DNS-320LW, DNS-321, DNR-322L, DNS-323, DNS-325, DNS-326, DNS-327L, DNR-326, DNS-340L, DNS-343, DNS-345, DNS-726-4, DNS-1100-4, DNS-1200-05 and DNS-1550-04 up to 20260205. The impacted element is the function cgi_refresh_db/FTP_Server_BlockIP_Add/FTP_Server_BlockIP_Del of the file /cgi-bin/app_mgr.cgi. Such manipulation leads to command injection. The attack can be executed remotely. The exploit has been disclosed to the public and may be used.

Affected products

• D-Link Dnr-202l Firmware: up to and including 2026-02-05
• D-Link Dnr-326 Firmware: up to and including 2026-02-05
• D-Link DNS-1100-4 Firmware: up to and including 2026-02-05
• D-Link DNS-1200-05 Firmware: up to and including 2026-02-05
• D-Link DNS-120 Firmware: up to and including 2026-02-05
• D-Link DNS-1550-04 Firmware: up to and including 2026-02-05
• D-Link DNS-315l Firmware: up to and including 2026-02-05
• D-Link DNS-320 Firmware: up to and including 2026-02-05
• D-Link DNS-320l Firmware: up to and including 2026-02-05
• D-Link DNS-320lw Firmware: up to and including 2026-02-05
• D-Link DNS-321 Firmware: up to and including 2026-02-05
• D-Link DNS-322l Firmware: up to and including 2026-02-05
• D-Link DNS-323 Firmware: up to and including 2026-02-05
• D-Link DNS-325 Firmware: up to and including 2026-02-05
• D-Link DNS-326 Firmware: up to and including 2026-02-05
• D-Link DNS-327l Firmware: up to and including 2026-02-05
• D-Link DNS-340l Firmware: up to and including 2026-02-05
• D-Link DNS-343 Firmware: up to and including 2026-02-05
• D-Link DNS-345 Firmware: up to and including 2026-02-05
• D-Link DNS-726-4 Firmware: up to and including 2026-02-05

Published 2026-03-16. Last modified 2026-06-17.