CVE-2021-29441: Authentication Bypass by Spoofing

Nacos is a platform designed for dynamic service discovery and configuration and service management. In Nacos, when configured to use authentication -Dnacos.core.auth.enabled=true it uses the AuthFilter servlet filter to enforce authentication. This filter has a backdoor that enables Nacos servers to bypass this filter and therefore skip authentication checks. This mechanism relies on the user-agent HTTP header so it can be easily spoofed. This issue may allow any user to carry out any administrative tasks on the Nacos server.