diff --git a/x-pack/plugins/elastic_assistant/server/routes/knowledge_base/entries/utils.test.ts b/x-pack/plugins/elastic_assistant/server/routes/knowledge_base/entries/utils.test.ts
new file mode 100644
index 0000000000000..e718ff44630c7
--- /dev/null
+++ b/x-pack/plugins/elastic_assistant/server/routes/knowledge_base/entries/utils.test.ts
@@ -0,0 +1,43 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { AuthenticatedUser } from '@kbn/core-security-common';
+import { getKBUserFilter } from './utils';
+
+describe('Utils', () => {
+  describe('getKBUserFilter', () => {
+    it('should return global filter when user is null', () => {
+      const filter = getKBUserFilter(null);
+      expect(filter).toEqual('(NOT users: {name:* OR id:* })');
+    });
+
+    it('should return global filter when `username` and `profile_uid` are undefined', () => {
+      const filter = getKBUserFilter({} as AuthenticatedUser);
+      expect(filter).toEqual('(NOT users: {name:* OR id:* })');
+    });
+
+    it('should return global filter when `username` is undefined', () => {
+      const filter = getKBUserFilter({ profile_uid: 'fake_user_id' } as AuthenticatedUser);
+      expect(filter).toEqual('(NOT users: {name:* OR id:* } OR users: {id: fake_user_id})');
+    });
+
+    it('should return global filter when `profile_uid` is undefined', () => {
+      const filter = getKBUserFilter({ username: 'user1' } as AuthenticatedUser);
+      expect(filter).toEqual('(NOT users: {name:* OR id:* } OR users: {name: "user1"})');
+    });
+
+    it('should return global filter when `username` has semicolon', () => {
+      const filter = getKBUserFilter({
+        username: 'user:1',
+        profile_uid: 'fake_user_id',
+      } as AuthenticatedUser);
+      expect(filter).toEqual(
+        '(NOT users: {name:* OR id:* } OR (users: {name: "user:1"} OR users: {id: fake_user_id}))'
+      );
+    });
+  });
+});
diff --git a/x-pack/plugins/elastic_assistant/server/routes/knowledge_base/entries/utils.ts b/x-pack/plugins/elastic_assistant/server/routes/knowledge_base/entries/utils.ts
index 3a548cd812539..0f5a0ab97fb29 100644
--- a/x-pack/plugins/elastic_assistant/server/routes/knowledge_base/entries/utils.ts
+++ b/x-pack/plugins/elastic_assistant/server/routes/knowledge_base/entries/utils.ts
@@ -11,7 +11,7 @@ export const getKBUserFilter = (user: AuthenticatedUser | null) => {
   // Only return the current users entries and all other global entries (where user[] is empty)
   const globalFilter = 'NOT users: {name:* OR id:* }';
 
-  const nameFilter = user?.username ? `users: {name: ${user?.username}}` : '';
+  const nameFilter = user?.username ? `users: {name: "${user?.username}"}` : '';
   const idFilter = user?.profile_uid ? `users: {id: ${user?.profile_uid}}` : '';
   const userFilter =
     user?.username && user?.profile_uid