Linksys WRT1900ACS

A vulnerability has been found in Linksys WRT1900ACS, EA7200, EA7450 and EA7500 up to 20250619 and classified as critical. This vulnerability affects the function SetDefaultConnectionService of the file /upnp/control/Layer3Forwarding of the component IGD. The manipulation of the argument NewDefaultConnectionService leads to stack-based buffer overflow. The attack can be initiated remotely. The exploit has been disclosed to the public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

An issue was discovered on Linksys WRT1900ACS 1.0.3.187766 devices. An ability exists for an unauthenticated user to browse a confidential ui/1.0.99.187766/dynamic/js/setup.js.localized file on the router's webserver, allowing for an attacker to identify possible passwords that the system uses to set the default guest network password. An attacker can use this list of 30 words along with a random 2 digit number to brute force their access onto a router's guest network.

An issue was discovered on Linksys WRT1900ACS 1.0.3.187766 devices. A lack of encryption in how the user login cookie (admin-auth) is stored on a victim's computer results in the admin password being discoverable by a local attacker, and usable to gain administrative access to the victim's router. The admin password is stored in base64 cleartext in an "admin-auth" cookie. An attacker sniffing the network at the time of login could acquire the router's admin password. Alternatively, gaining physical access to the victim's computer soon after an administrative login could result in compromise.