Authenticating requests from iframe

I have an iframe with a dropdown menu that contains the projects when I select one and return the information I get
“status”: 401, “error”: “Unauthorized”, “message”: “No message available”, “timeStamp”: “Wed Oct 31 16:27:26 VET 2018”, “trace”: null}

<form class="aui" th:action="@{/data(jwt=${atlassianConnectToken})}"  method="post">
				<div class="field-group">
					<label for="select-example">Dropdown</label>
					<select class="select" id="select-example" name="select-example">
						<option>Select Project</option>
							<option th:each="pro : ${Listap}"
                				th:value="${pro.id}"
                				th:text="${pro.name}">
                			</option>
					</select>
				</div>
				<button class="aui-button aui-button-primary" >Buscar</button>
			</form>