Description

A newly uncovered and critical security flaw, identified as CVE-2025-4978 with a CVSSv4 score of 9.3, has been found in NETGEAR’s DGND3700v2 router. This vulnerability enables remote attackers to bypass authentication entirely through a suspected backdoor in the device’s web interface. The flaw exists within the router’s embedded mini_http server, where an unprotected endpoint /BRS_top.html triggers an internal flag that disables HTTP Basic Authentication. Security researcher at0de, who identified the vulnerability, noted that accessing the specific endpoint triggers a variable named start_in_blankstate, setting its value to 1. This flag is later referenced in the function handling login validation, causing the router to skip standard authentication checks. Once triggered, this mechanism grants full access to the router's web-based administrative interface without requiring any credentials, essentially leaving the device defenseless. This means anyone with network access to the device either locally or through enabled remote management can manipulate its configuration. An attacker could modify DNS settings to reroute traffic, deploy persistent malware, extract stored credentials from connected devices, or disable critical protections like firewalls and parental controls. The ease of exploiting this backdoor, coupled with its broad access privileges, makes it particularly dangerous for home and small business environments. The identified vulnerability affects NETGEAR’s DGND3700v2 router using firmware version V1.1.00.15_1.00.15NA, leaving the device vulnerable to full unauthorized access. Systems running this firmware are exposed to serious security risks due to the flaw. Without prompt firmware updates, these routers remain open to exploitation, emphasizing the urgent need for users to apply the latest security patch. Updating to the latest version is critical to prevent potential intrusions and safeguard sensitive network configurations.