Fix security issue in mermaid markdown

Add data attr to close issue link
and avoid getting url from href
which can be set via mermaid

app/assets/javascripts/issue.js

@@ -108,7 +108,11 @@ export default class Issue {
         } else {
           this.disableCloseReopenButton($button);
 
-          const url = $button.attr('href');
+          const url = $button.data('close-reopen-url');
+          if (!url) {
+            return;
+          }
+
           return axios
             .put(url)
             .then(({ data }) => {

app/views/shared/issuable/_close_reopen_report_toggle.html.haml

@@ -11,7 +11,7 @@
 
 .float-left.btn-group.prepend-left-10.issuable-close-dropdown.droplab-dropdown.js-issuable-close-dropdown
   = link_to "#{display_button_action} #{display_issuable_type}", close_reopen_issuable_path(issuable),
-            method: button_method, class: "#{button_class} btn-#{button_action} #{(add_blocked_class ? 'btn-issue-blocked' : '')}", title: "#{display_button_action} #{display_issuable_type}", data: { qa_selector: 'close_issue_button' }
+            method: button_method, class: "#{button_class} btn-#{button_action} #{(add_blocked_class ? 'btn-issue-blocked' : '')}", title: "#{display_button_action} #{display_issuable_type}", data: { qa_selector: 'close_issue_button', 'close-reopen-url': close_reopen_issuable_path(issuable) }
 
   = button_tag type: 'button', class: "#{toggle_class} btn-#{button_action}-color",
                data: { 'dropdown-trigger' => '#issuable-close-menu' }, 'aria-label' => _('Toggle dropdown') do

changelogs/unreleased/security-fix-mermaid-issue.yml

+---
+title: Disallow user to control PUT request using mermaid markdown in issue description
+merge_request:
+author:
+type: security

ee/app/views/projects/issues/_alert_blocked.html.haml

@@ -10,6 +10,6 @@
       = _('This issue is currently blocked by the following issues: %{issues}.').html_safe % { issues: blocked_by_issues_links }
     .gl-alert-actions
       = link_to _("Yes, close issue"), close_issuable_path(issue), rel: 'nofollow', method: '',
-                class: "btn btn-close-anyway gl-alert-action btn-warning btn-md gl-button", title: _("Yes, close issue")
+                class: "btn btn-close-anyway gl-alert-action btn-warning btn-md gl-button", title: _("Yes, close issue"), 'data-close-reopen-url' => close_issuable_path(issue)
       %button.btn.gl-alert-action.btn-warning.btn-md.gl-button.btn-secondary
         = s_('Cancel')

spec/frontend/fixtures/static/issue_with_mermaid_graph.html

+<div class="description" updated-at="">
+  <div class="md issue-realtime-trigger-pulse">
+    <svg
+      id="mermaid-1587752414912"
+      width="100%"
+      xmlns="http://www.w3.org/2000/svg"
+      style="max-width: 185.35000610351562px;"
+      viewBox="0 0 185.35000610351562 50.5"
+      class="mermaid"
+    >
+      <g transform="translate(0, 0)">
+        <g class="output">
+          <g class="clusters"></g>
+          <g class="edgePaths"></g>
+          <g class="edgeLabels"></g>
+          <g class="nodes">
+            <g
+              class="node js-issuable-actions btn-close clickable"
+              style="opacity: 1;"
+              id="A"
+              transform="translate(92.67500305175781,25.25)"
+              title="click to PUT"
+            >
+              <a
+                class="js-issuable-actions btn-close clickable"
+                href="https://invalid"
+                rel="noopener"
+              >
+                <rect
+                  rx="0"
+                  ry="0"
+                  x="-84.67500305175781"
+                  y="-17.25"
+                  width="169.35000610351562"
+                  height="34.5"
+                  class="label-container"
+                ></rect>
+                <g class="label" transform="translate(0,0)">
+                  <g transform="translate(-74.67500305175781,-7.25)">
+                    <text style="">
+                      <tspan xml:space="preserve" dy="1em" x="1">Click to send a PUT request</tspan>
+                    </text>
+                  </g>
+                </g>
+              </a>
+            </g>
+          </g>
+        </g>
+      </g>
+      <text class="source" display="none">
+        Click to send a PUT request
+      </text>
+    </svg>
+  </div>
+  <textarea
+    data-update-url="/h5bp/html5-boilerplate/-/issues/35.json"
+    dir="auto"
+    class="hidden js-task-list-field"
+  ></textarea>
+  <div class="modal-open recaptcha-modal js-recaptcha-modal" style="display: none;">
+    <div role="dialog" tabindex="-1" class="modal d-block">
+      <div role="document" class="modal-dialog">
+        <div class="modal-content">
+          <div class="modal-header">
+            <h4 class="modal-title float-left">Please solve the reCAPTCHA</h4>
+            <button type="button" data-dismiss="modal" aria-label="Close" class="close float-right">
+              <span aria-hidden="true">×</span>
+            </button>
+          </div>
+          <div class="modal-body">
+            <div>
+              <p>We want to be sure it is you, please confirm you are not a robot.</p>
+              <div></div>
+            </div>
+          </div>
+          <!---->
+        </div>
+      </div>
+    </div>
+    <div class="modal-backdrop fade show"></div>
+  </div>
+</div>

spec/frontend/issue_spec.js

@@ -18,6 +18,7 @@ describe('Issue', () => {
   preloadFixtures('issues/closed-issue.html');
   preloadFixtures('issues/issue-with-task-list.html');
   preloadFixtures('issues/open-issue.html');
+  preloadFixtures('static/issue_with_mermaid_graph.html');
 
   function expectErrorMessage() {
     const $flashMessage = $('div.flash-alert');
@@ -228,4 +229,30 @@ describe('Issue', () => {
       });
     });
   });
+
+  describe('when not displaying blocked warning', () => {
+    describe('when clicking a mermaid graph inside an issue description', () => {
+      let mock;
+      let spy;
+
+      beforeEach(() => {
+        loadFixtures('static/issue_with_mermaid_graph.html');
+        mock = new MockAdapter(axios);
+        spy = jest.spyOn(axios, 'put');
+      });
+
+      afterEach(() => {
+        mock.restore();
+        jest.clearAllMocks();
+      });
+
+      it('does not make a PUT request', () => {
+        Issue.prototype.initIssueBtnEventListeners();
+
+        $('svg a.js-issuable-actions').trigger('click');
+
+        expect(spy).not.toHaveBeenCalled();
+      });
+    });
+  });
 });