diff --git a/client/src/views/site/navbar.js b/client/src/views/site/navbar.js
index e8b533f34c..50ae825bd4 100644
--- a/client/src/views/site/navbar.js
+++ b/client/src/views/site/navbar.js
@@ -1286,6 +1286,13 @@ 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'])
         }