diff --git a/client/src/views/site/navbar.js b/client/src/views/site/navbar.js
index 0ca3107f0c..5b626712a2 100644
--- a/client/src/views/site/navbar.js
+++ b/client/src/views/site/navbar.js
@@ -1313,6 +1313,13 @@ class NavbarSiteView extends View {
             color = this.getMetadata().get(['clientDefs', tab, 'color']);
         }
 
+        if (
+            color &&
+            !/^#([0-9A-Fa-f]{3}|[0-9A-Fa-f]{6})$/.test(color)
+        ) {
+            color = null;
+        }
+
         if (!params.tabIconsDisabled && !isGroup && !isDivider && !isUrl) {
             iconClass = this.getMetadata().get(['clientDefs', tab, 'iconClass'])
         }
diff --git a/package-lock.json b/package-lock.json
index 4e14a77a42..94a46dafc7 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "espocrm",
-  "version": "9.0.5",
+  "version": "9.0.6",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "espocrm",
-      "version": "9.0.5",
+      "version": "9.0.6",
       "hasInstallScript": true,
       "license": "AGPL-3.0-or-later",
       "dependencies": {
diff --git a/package.json b/package.json
index e552f17604..8d737668c3 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "espocrm",
-  "version": "9.0.5",
+  "version": "9.0.6",
   "description": "Open-source CRM.",
   "repository": {
     "type": "git",