New research shows that behaviors that occur at the very lowest levels of the network stack make encryption—in any form, not just those that have been broken in the past—incapable of providing client isolation, an encryption-enabled protection promised by all router makers, that is intended to block direct communication between two or more connected clients.

The isolation can effectively be nullified through AirSnitch, the name the researchers gave to a series of attacks that capitalize on the newly discovered weaknesses. Various forms of AirSnitch work across a broad range of routers, including those from Netgear, D-Link, Ubiquiti, Cisco, and those running DD-WRT and OpenWrt.

AirSnitch “breaks worldwide Wi-Fi encryption, and it might have the potential to enable advanced cyberattacks,” Xin’an Zhou, the lead author of the research paper, said in an interview. “Advanced attacks can build on our primitives to [perform] cookie stealing, DNS and cache poisoning. Our research physically wiretaps the wire altogether so these sophisticated attacks will work. It’s really a threat to worldwide network security.” Zhou presented his research on Wednesday at the 2026 Network and Distributed System Security Symposium.

Unlike previous Wi-Fi attacks, AirSnitch exploits core features in Layers 1 and 2 and the failure to bind and synchronize a client across these and higher layers, other nodes, and other network names such as SSIDs (Service Set Identifiers). This cross-layer identity desynchronization is the key driver of AirSnitch attacks.

The most powerful such attack is a full, bidirectional machine-in-the-middle (MitM) attack, meaning the attacker can view and modify data before it makes its way to the intended recipient. The attacker can be on the same SSID, a separate one, or even a separate network segment tied to the same AP. It works against small Wi-Fi networks in both homes and offices and large networks in enterprises.

With the ability to intercept all link-layer traffic (that is, the traffic as it passes between Layers 1 and 2), an attacker can perform other attacks on higher layers. The most dire consequence occurs when an Internet connection isn’t encrypted—something that Google recently estimated occurred when as much as 6 percent and 20 percent of pages loaded on Windows and Linux, respectively. In these cases, the attacker can view and modify all traffic in the clear and steal authentication cookies, passwords, payment card details, and any other sensitive data. Since many company intranets are sent in plaintext, traffic from them can also be intercepted.

Even when HTTPS is in place, an attacker can still intercept domain look-up traffic and use DNS cache poisoning to corrupt tables stored by the target’s operating system. The AirSnitch MitM also puts the attacker in the position to wage attacks against vulnerabilities that may not be patched. Attackers can also see the external IP addresses hosting webpages being visited and often correlate them with the precise URL.