ollama - 💡(How to fix) Fix HIGH: Cloud proxy forwards X-Forwarded-For and X-Real-IP — clients can spoof origin IP to ollama.com

CWE-348: Cloud Proxy Forwards Untrusted Client Headers — IP Spoofing / Request Forgery

Severity: HIGH (CVSS 7.5)

Location

server/cloud_proxy.go — copyProxyRequestHeaders():

func copyProxyRequestHeaders(dst, src http.Header) {
    connectionTokens := connectionHeaderTokens(src)
    for key, values := range src {
        if isHopByHopHeader(key) || isConnectionTokenHeader(key, connectionTokens) {
            continue
        }
        dst.Del(key)
        for _, value := range values {
            dst.Add(key, value)
        }
    }
}

Only hop-by-hop headers (Connection, Keep-Alive, Transfer-Encoding, etc.) are stripped. All other client-supplied headers are forwarded verbatim to ollama.com including:

• X-Forwarded-For
• X-Forwarded-Host
• X-Forwarded-Proto
• X-Real-IP
• Forwarded
• X-Forwarded-Port

Impact

An attacker sending requests through the cloud proxy can:

1. Spoof origin IP by setting X-Forwarded-For: 1.2.3.4 — bypassing rate limits, IP bans, or geographic restrictions on ollama.com
2. Forge request origin — upstream services see spoofed client metadata
3. Inject arbitrary HTTP headers that affect upstream request processing
4. Bypass abuse detection — make malicious traffic appear to come from trusted IPs

This affects all cloud-proxied endpoints:

• /api/generate / /api/chat (when model is :cloud)
• /v1/chat/completions / /v1/completions / /v1/embeddings
• /v1/images/generations / /v1/images/edits
• /v1/messages

Remediation

Strip proxy/source headers from the incoming client request before forwarding:

var clientProxyHeaders = []string{
    "Forwarded",
    "X-Forwarded-For",
    "X-Forwarded-Host",
    "X-Forwarded-Proto",
    "X-Forwarded-Port",
    "X-Real-IP",
    "X-Request-ID",
    "X-Client-IP",
}

func copyProxyRequestHeaders(dst, src http.Header) {
    // ... existing hop-by-hop logic ...
    for _, h := range clientProxyHeaders {
        dst.Del(h)
    }
}