GHSA-RJR7-JGGH-PGCP

chi's RealIP Middleware allows IP spoofing via unvalidated X-Forwarded-For header

func realIP(r *http.Request) string {
    var ip string
    if tcip := r.Header.Get(trueClientIP); tcip != "" {
        ip = tcip  // controlled by attacker
    } else if xrip := r.Header.Get(xRealIP); xrip != "" {
        ip = xrip  // controlled by attacker
    } else if xff := r.Header.Get(xForwardedFor); xff != "" {
        ip, _, _ = strings.Cut(xff, ",")  // controlled by attacker
    }
    // ...
    return ip
}

package main

import (
    "fmt"
    "net/http"
    "github.com/go-chi/chi/v5"
    "github.com/go-chi/chi/v5/middleware"
)

func main() {
    r := chi.NewRouter()
    r.Use(middleware.RealIP)

    r.Get("/admin", func(w http.ResponseWriter, r *http.Request) {
        // ip-based access control got bypassed
        if r.RemoteAddr == "127.0.0.1" {
            w.Write([]byte("SECRET ADMIN DATA"))
            return
        }
        http.Error(w, "Forbidden", 403)
    })

    http.ListenAndServe(":8080", r)
}

curl -H "X-Forwarded-For: 127.0.0.1" http://localhost:8080/admin

// add your reverse proxy ip addresses here
var trustedProxies = []net.IPNet{
       {IP: net.ParseIP("10.0.0.0"), Mask: net.CIDRMask(8, 32)},
    {IP: net.ParseIP("172.16.0.0"), Mask: net.CIDRMask(12, 32)},
    {IP: net.ParseIP("192.168.0.0"), Mask: net.CIDRMask(16, 32)},
}

func isTrustedProxy(ip net.IP) bool {
    for _, cidr := range trustedProxies {
        if cidr.Contains(ip) {
            return true
        }
    }
    return false
}

• ip-based access control bypass lets attackers reach restricted endpoints
• rate limiting bypass lets attackers avoid limits by rotating spoofed ips
• audit logs show fake ips picked by attacker instead of real ones
• attackers can get around geo ip restrictions

Kodem intelligence

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1. What is GHSA-RJR7-JGGH-PGCP? GHSA-RJR7-JGGH-PGCP is a high-severity security vulnerability in github.com/go-chi/chi/middleware (go), affecting versions <= 1.5.5. It is fixed in 5.3.0.
2. Which packages are affected by GHSA-RJR7-JGGH-PGCP?
   • github.com/go-chi/chi/middleware (go) (versions <= 1.5.5)
   • github.com/go-chi/chi/v2/middleware (go) (versions <= 2.1.1)
   • github.com/go-chi/chi/v3/middleware (go) (versions <= 3.3.5)
   • github.com/go-chi/chi/v4/middleware (go) (versions <= 4.1.3)
   • github.com/go-chi/chi/v5/middleware (go) (versions < 5.3.0)
3. Is there a fix for GHSA-RJR7-JGGH-PGCP? Yes. GHSA-RJR7-JGGH-PGCP is fixed in 5.3.0. Upgrade to this version or later.
4. Is GHSA-RJR7-JGGH-PGCP exploitable, and should I be worried? Whether GHSA-RJR7-JGGH-PGCP is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
5. What actually determines whether GHSA-RJR7-JGGH-PGCP is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
6. How do I fix GHSA-RJR7-JGGH-PGCP? Upgrade github.com/go-chi/chi/v5/middleware to 5.3.0 or later.

Other vulnerabilities in github.com/go-chi/chi/middleware