diff --git a/packages/frontend/src/components/MkSignupDialog.rules.vue b/packages/frontend/src/components/MkSignupDialog.rules.vue
index 9e2d7821d5..b7476c6598 100644
--- a/packages/frontend/src/components/MkSignupDialog.rules.vue
+++ b/packages/frontend/src/components/MkSignupDialog.rules.vue
@@ -24,7 +24,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 				<template #suffix><i v-if="agreeServerRules" class="ph-check ph-bold ph-lg" style="color: var(--success)"></i></template>
 
 				<ol class="_gaps_s" :class="$style.rules">
-					<li v-for="item in instance.serverRules" :class="$style.rule"><div :class="$style.ruleText" v-html="item"></div></li>
+					<li v-for="item in instance.serverRules" :class="$style.rule"><div :class="$style.ruleText" v-html="sanitizeHtml(item)"></div></li>
 				</ol>
 
 				<MkSwitch :modelValue="agreeServerRules" style="margin-top: 16px;" @update:modelValue="updateAgreeServerRules">{{ i18n.ts.agree }}</MkSwitch>
@@ -65,6 +65,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 import { computed, ref } from 'vue';
 import { instance } from '@/instance.js';
 import { i18n } from '@/i18n.js';
+import sanitizeHtml from 'sanitize-html';
 import MkButton from '@/components/MkButton.vue';
 import MkFolder from '@/components/MkFolder.vue';
 import MkSwitch from '@/components/MkSwitch.vue';
diff --git a/packages/frontend/src/components/MkVisitorDashboard.vue b/packages/frontend/src/components/MkVisitorDashboard.vue
index 11707b07f3..2d6e0b59f5 100644
--- a/packages/frontend/src/components/MkVisitorDashboard.vue
+++ b/packages/frontend/src/components/MkVisitorDashboard.vue
@@ -16,7 +16,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 			</h1>
 			<div :class="$style.mainAbout">
 				<!-- eslint-disable-next-line vue/no-v-html -->
-				<div v-html="meta.description || i18n.ts.headlineMisskey"></div>
+				<div v-html="sanitizeHtml(meta.description) || i18n.ts.headlineMisskey"></div>
 			</div>
 			<div v-if="instance.disableRegistration" :class="$style.mainWarn">
 				<MkInfo warn>{{ i18n.ts.invitationRequiredToRegister }}</MkInfo>
@@ -56,6 +56,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 <script lang="ts" setup>
 import { ref } from 'vue';
 import * as Misskey from 'misskey-js';
+import sanitizeHtml from 'sanitize-html';
 import XSigninDialog from '@/components/MkSigninDialog.vue';
 import XSignupDialog from '@/components/MkSignupDialog.vue';
 import MkButton from '@/components/MkButton.vue';
diff --git a/packages/frontend/src/pages/about.vue b/packages/frontend/src/pages/about.vue
index 542be034ba..8e4ea8f12f 100644
--- a/packages/frontend/src/pages/about.vue
+++ b/packages/frontend/src/pages/about.vue
@@ -20,7 +20,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 
 				<MkKeyValue>
 					<template #key>{{ i18n.ts.description }}</template>
-					<template #value><div v-html="instance.description"></div></template>
+					<template #value><div v-html="sanitizeHtml(instance.description)"></div></template>
 				</MkKeyValue>
 
 				<FormSection>
@@ -53,7 +53,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 								<template #label>{{ i18n.ts.serverRules }}</template>
 
 								<ol class="_gaps_s" :class="$style.rules">
-									<li v-for="item, index in instance.serverRules" :key="index" :class="$style.rule"><div :class="$style.ruleText" v-html="item"></div></li>
+									<li v-for="item, index in instance.serverRules" :key="index" :class="$style.rule"><div :class="$style.ruleText" v-html="sanitizeHtml(item)"></div></li>
 								</ol>
 							</MkFolder>
 							<FormLink v-if="instance.tosUrl" :to="instance.tosUrl" external>{{ i18n.ts.termsOfService }}</FormLink>
@@ -105,6 +105,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 </template>
 
 <script lang="ts" setup>
+import sanitizeHtml from 'sanitize-html';
 import { computed, watch, ref } from 'vue';
 import * as Misskey from 'misskey-js';
 import XEmojis from './about.emojis.vue';