CROSS-SITE WEBSOCKET HIJACKING EXPLOITATION IN 2025

Summary from the TLDR InfoSec newsletter

Cross-Site WebSocket Hijacking is a vulnerability that arises from WebSockets being unprotected by the Same Origin Policy, allowing malicious sites to connect to targeted sites impersonating the user. Modern browsers have implemented security features that make CSWSH harder to exploit, such as Chrome's SameSite=Lax default cookie and Firefox's Total Cookie Protection. However, proper Origin validation during the server-side WebSocket handshake is the most reliable defense, as browser settings can change, and Chrome still permits CSWSH under certain conditions.