Improper exposure of client IP addresses in net/http before Go 1.17.12 and Go 1.18.4 can be triggered by calling httputil.ReverseProxy.ServeHTTP with a Request.Header map containing a nil value for the X-Forwarded-For header, which causes ReverseProxy to set the client IP as the value of the X-Forwarded-For header.
https://pkg.go.dev/vuln/GO-2022-0520
https://groups.google.com/g/golang-announce/c/nqrv9fbR0zE
https://go.googlesource.com/go/+/b2cc0fecc2ccd80e6d5d16542cc684f97b3a9c8a