Zero-Day Alert: Linksys Auth Bypass Lets Hackers Hijack Routers Without Passwords

According to CSIT, a zero-day vulnerability in the Linksys E9450-SG router, tracked as CVE-2025-52692, allows attackers on the local network to bypass authentication and enable the device’s Telnet server with no password required. The flaw stems from how the router parses web requests, enabling access to authentication‑protected endpoints by manipulating the URL, specifically via the path /LOGIN/API/obj/en_telnet.

Once triggered, the router silently enables Telnet, giving an attacker log‑in with root privileges and the ability to execute commands. The vulnerability has been verified in firmware version 1.2.00.052, which CSIT notes is the only firmware version released thus far for this model variant, and the attack is not remotely exploitable over the internet by default, requiring prior access to the router’s administrative web interface.

It is largely limited to attackers who have already gained access to the victim’s Wi‑Fi network, and the report highlights that consumer routers are attractive targets due to exposing internal networks and often containing flaws. Singtel distributed the device in 2021, a detail noted in the disclosure.