diff --git a/src/modal/modal.ts b/src/modal/modal.ts
index 81f4783..dc349a2 100644
--- a/src/modal/modal.ts
+++ b/src/modal/modal.ts
@@ -632,16 +632,22 @@ export class CaptureEyeModal extends LitElement {
     );
   }
 
+  private isValidColor(color: string): boolean {
+    return CSS.supports('color', color.trim());
+  }
+
   private updateModalColor() {
-    // Set primary color
-    this.style.setProperty('--primary-color', this._color);
+    // Clear colors first; set only if color is valid
+    this.style.setProperty('--primary-color', '');
+    this.style.setProperty('--hover-color', '');
 
-    // Set hover color
-    this.style.setProperty('--hover-color', '');  // Clear the color
-    if (!this._color) {
+    if (!this._color || !this.isValidColor(this._color)) {
       return;
     }
 
+    // Set primary color
+    this.style.setProperty('--primary-color', this._color);
+
     const ctx = document.createElement('canvas').getContext('2d');
     if (!ctx) {
       return;
diff --git a/src/test/modal_test.ts b/src/test/modal_test.ts
index 29a064d..c6e1875 100644
--- a/src/test/modal_test.ts
+++ b/src/test/modal_test.ts
@@ -526,4 +526,62 @@ suite('capture-eye-modal', () => {
     buttonCr = el.shadowRoot!.querySelector('.button-content-credentials');
     assert.notExists(buttonCr);
   });
+
+  suite('updateModalColor color validation', () => {
+    test('sets --primary-color for valid hex color', async () => {
+      const el = await fixture<CaptureEyeModal>(html`
+        <capture-eye-modal></capture-eye-modal>
+      `);
+      el.updateModalOptions({ nid: '1', color: '#027fe5' });
+      await el.updateComplete;
+      assert.equal(el.style.getPropertyValue('--primary-color'), '#027fe5');
+    });
+
+    test('sets --primary-color for valid short hex color', async () => {
+      const el = await fixture<CaptureEyeModal>(html`
+        <capture-eye-modal></capture-eye-modal>
+      `);
+      el.updateModalOptions({ nid: '1', color: '#fff' });
+      await el.updateComplete;
+      assert.equal(el.style.getPropertyValue('--primary-color'), '#fff');
+    });
+
+    test('sets --primary-color for valid named color', async () => {
+      const el = await fixture<CaptureEyeModal>(html`
+        <capture-eye-modal></capture-eye-modal>
+      `);
+      el.updateModalOptions({ nid: '1', color: 'red' });
+      await el.updateComplete;
+      assert.equal(el.style.getPropertyValue('--primary-color'), 'red');
+    });
+
+    test('does not set --primary-color for invalid color with semicolon injection', async () => {
+      const el = await fixture<CaptureEyeModal>(html`
+        <capture-eye-modal></capture-eye-modal>
+      `);
+      el.updateModalOptions({ nid: '1', color: 'red; --injected: value' });
+      await el.updateComplete;
+      assert.equal(el.style.getPropertyValue('--primary-color'), '');
+    });
+
+    test('does not set --primary-color for arbitrary string', async () => {
+      const el = await fixture<CaptureEyeModal>(html`
+        <capture-eye-modal></capture-eye-modal>
+      `);
+      el.updateModalOptions({ nid: '1', color: 'not-a-color' });
+      await el.updateComplete;
+      assert.equal(el.style.getPropertyValue('--primary-color'), '');
+    });
+
+    test('clears --primary-color when color is empty', async () => {
+      const el = await fixture<CaptureEyeModal>(html`
+        <capture-eye-modal></capture-eye-modal>
+      `);
+      el.updateModalOptions({ nid: '1', color: '#027fe5' });
+      await el.updateComplete;
+      el.updateModalOptions({ nid: '1', color: '' });
+      await el.updateComplete;
+      assert.equal(el.style.getPropertyValue('--primary-color'), '');
+    });
+  });
 });