Technical impact
The vulnerability resides in the ftpd_conf.php file of the FTP Daemon. The file uses hard‑coded credentials, allowing a remote attacker to authenticate with known user names and passwords. Once authenticated, the attacker gains the same level of access as those credentials, which can include the ability to read and modify files on the device or, if the device exposes additional services, to further compromise the router.
Affected Systems
The flaw affects D-Link DSL‑6740C routers running firmware version 20131126. No other versions were listed as affected in the CNA data.
Risk and Exploitability
The CVSS score of 10 indicates critical severity. The exploit is publicly available, so the actual exploitation likelihood is high even though the EPSS score is not listed. As the flaw is exploitable remotely, attackers can reach affected devices from the Internet by connecting to the FTP service. The flaw is not in the CISA KEV catalog, but the combination of hard‑coded credentials and remote reachability makes it a high‑priority issue.
