diff --git a/src/scriptlets/inject-css-in-shadow-dom.js b/src/scriptlets/inject-css-in-shadow-dom.js
index 72a9f558..bed72ccc 100644
--- a/src/scriptlets/inject-css-in-shadow-dom.js
+++ b/src/scriptlets/inject-css-in-shadow-dom.js
@@ -39,6 +39,12 @@ export function injectCssInShadowDom(source, cssRule, hostSelector = '') {
         return;
     }
 
+    // url() css function is not allowed
+    if (cssRule.match(/url\(.*\)/i)) {
+        logMessage(source, '"url()" function is not allowed for css rules');
+        return;
+    }
+
     const callback = (shadowRoot) => {
         const stylesheet = new CSSStyleSheet();
         try {
diff --git a/tests/scriptlets/inject-css-in-shadow-dom.test.js b/tests/scriptlets/inject-css-in-shadow-dom.test.js
index 7b93f78f..6cd6d345 100644
--- a/tests/scriptlets/inject-css-in-shadow-dom.test.js
+++ b/tests/scriptlets/inject-css-in-shadow-dom.test.js
@@ -1,18 +1,21 @@
-/* eslint-disable no-underscore-dangle */
+/* eslint-disable no-underscore-dangle, no-console */
 import { runScriptlet, clearGlobalProps } from '../helpers';
 
 const { test, module } = QUnit;
 const name = 'inject-css-in-shadow-dom';
 
 const nativeAttachShadow = window.Element.prototype.attachShadow;
+const nativeConsole = console.log;
 
 const TARGET_ID1 = 'target1';
 const CSS_TEXT1 = `#${TARGET_ID1} { color: rgb(255, 0, 0)  !important }`;
+const CSS_TEXT2 = `#${TARGET_ID1} { background: lightblue url("https://www.w3schools.com/cssref/img_tree.gif"); }  !important }`;
+const INVALID_CSS_TEXT = `#${TARGET_ID1} { color: rgb(255, 0, 0) } !important`;
 const HOST_ID1 = 'host1';
 const HOST_ID2 = 'host2';
 
 const appendTarget = (parent, id) => {
-    const target = document.createElement('h1');
+    const target = document.createElement('div');
     target.id = id;
     target.innerText = id;
     return parent.appendChild(target);
@@ -44,6 +47,7 @@ const afterEach = () => {
     clearGlobalProps('hit', '__debug');
     removeHosts();
     window.Element.prototype.attachShadow = nativeAttachShadow;
+    console.log = nativeConsole;
 };
 
 module(name, { beforeEach, afterEach });
@@ -99,4 +103,58 @@ if (!isSupported) {
 
         assert.strictEqual(window.hit, 'FIRED', 'hit function was executed');
     });
+
+    test('do not apply style with url function, logged correctly', (assert) => {
+        assert.expect(3);
+        console.log = function log(input) {
+            if (input.indexOf('trace') > -1) {
+                return;
+            }
+            assert.strictEqual(
+                input,
+                `${name}: "url()" function is not allowed for css rules`,
+                'message logged correctly',
+            );
+        };
+
+        runScriptlet(name, [CSS_TEXT2]);
+
+        const host1 = appendHost(HOST_ID1);
+        const shadowRoot1 = host1.attachShadow({ mode: 'closed' });
+        appendTarget(shadowRoot1, TARGET_ID1);
+
+        // style with url() function should not be applied
+        const target1 = shadowRoot1.getElementById(TARGET_ID1);
+        const target1Background = getComputedStyle(target1).background;
+
+        assert.ok(!target1Background.match(/url\(.*\)/i), 'style was not applied to shadowRoot #1');
+        assert.strictEqual(window.hit, undefined, 'hit should NOT fire');
+    });
+
+    test('do not apply invalid style, logged correctly', (assert) => {
+        assert.expect(3);
+        console.log = function log(input) {
+            if (input.indexOf('trace') > -1) {
+                return;
+            }
+            assert.strictEqual(
+                input,
+                `${name}: Failed to parse the rule: ${INVALID_CSS_TEXT}`,
+                'message logged correctly',
+            );
+        };
+
+        runScriptlet(name, [INVALID_CSS_TEXT]);
+
+        const host1 = appendHost(HOST_ID1);
+        const shadowRoot1 = host1.attachShadow({ mode: 'closed' });
+        appendTarget(shadowRoot1, TARGET_ID1);
+
+        // style with url() function should not be applied
+        const target1 = shadowRoot1.getElementById(TARGET_ID1);
+        const target1Color = getComputedStyle(target1).color;
+
+        assert.strictEqual(target1Color, 'rgb(0, 0, 0)', 'style was not applied to shadowRoot #1');
+        assert.strictEqual(window.hit, undefined, 'hit should NOT fire');
+    });
 }