China-Linked Hackers Exploit Sogou One-Click RCE to Deploy GRAYRABBIT Backdoor

China-linked threat actors tracked as UNC3569 have exploited a critical one-click remote code execution vulnerability in Tencent’s Sogou Input Method for Windows to deploy the GRAYRABBIT backdoor on targeted systems. Tracked as CVE-2026-51990, the vulnerability chains an insecure custom protocol handler, unrestricted embedded-browser navigation,...