This template only works on Nuclei engine prior to version 2.3.3 and version >= 2.3.5. In Nacos before version 1.4.1, when configured to use authentication (-Dnacos.core.auth.enabled=true) Nacos 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.
View the template here CVE-2021-29441.yaml
References:
https://nvd.nist.gov/vuln/detail/CVE-2021-29441