diff --git a/packages/frontend/src/components/MkUrlPreview.vue b/packages/frontend/src/components/MkUrlPreview.vue
index 4689f5e77..f7677faf7 100644
--- a/packages/frontend/src/components/MkUrlPreview.vue
+++ b/packages/frontend/src/components/MkUrlPreview.vue
@@ -86,6 +86,7 @@ let tweetHeight = $ref(150);
 let unknownUrl = $ref(false);
 
 const requestUrl = new URL(props.url);
+if (!['http:', 'https:'].includes(requestUrl.protocol)) throw new Error('invalid url');
 
 if (requestUrl.hostname === 'twitter.com' || requestUrl.hostname === 'mobile.twitter.com') {
 	const m = requestUrl.pathname.match(/^\/.+\/status(?:es)?\/(\d+)/);
diff --git a/packages/frontend/src/components/MkYoutubePlayer.vue b/packages/frontend/src/components/MkYoutubePlayer.vue
index d1f1f9e9c..50d38a71b 100644
--- a/packages/frontend/src/components/MkYoutubePlayer.vue
+++ b/packages/frontend/src/components/MkYoutubePlayer.vue
@@ -26,6 +26,7 @@ const props = defineProps<{
 }>();
 
 const requestUrl = new URL(props.url);
+if (!['http:', 'https:'].includes(requestUrl.protocol)) throw new Error('invalid url');
 
 let fetching = $ref(true);
 let title = $ref<string | null>(null);
diff --git a/packages/frontend/src/components/global/MkUrl.vue b/packages/frontend/src/components/global/MkUrl.vue
index 27c8329dc..2a9278030 100644
--- a/packages/frontend/src/components/global/MkUrl.vue
+++ b/packages/frontend/src/components/global/MkUrl.vue
@@ -33,6 +33,7 @@ const props = defineProps<{
 
 const self = props.url.startsWith(local);
 const url = new URL(props.url);
+if (!['http:', 'https:'].includes(url.protocol)) throw new Error('invalid url');
 const el = ref();
 
 useTooltip(el, (showing) => {
diff --git a/packages/frontend/src/pages/miauth.vue b/packages/frontend/src/pages/miauth.vue
index a01c7c5c4..3debaeeb6 100644
--- a/packages/frontend/src/pages/miauth.vue
+++ b/packages/frontend/src/pages/miauth.vue
@@ -70,6 +70,7 @@ async function accept(): Promise<void> {
 	state = 'accepted';
 	if (props.callback) {
 		const cbUrl = new URL(props.callback);
+		if (!['http:', 'https:'].includes(cbUrl.protocol)) throw new Error('invalid url');
 		cbUrl.searchParams.set('session', props.session);
 		location.href = cbUrl.href;
 	}