diff --git a/apps/stage-tamagotchi-electron/src/renderer/pages/settings/airi-card/components/CardDetailDialog.vue b/apps/stage-tamagotchi-electron/src/renderer/pages/settings/airi-card/components/CardDetailDialog.vue
index 364714e86..a904406d2 100644
--- a/apps/stage-tamagotchi-electron/src/renderer/pages/settings/airi-card/components/CardDetailDialog.vue
+++ b/apps/stage-tamagotchi-electron/src/renderer/pages/settings/airi-card/components/CardDetailDialog.vue
@@ -1,6 +1,8 @@
 <script setup lang="ts">
 import type { AiriCard } from '@proj-airi/stage-ui/stores/modules/airi-card'
 
+import DOMPurify from 'dompurify'
+
 import { Button } from '@proj-airi/stage-ui/components'
 import { useAiriCardStore } from '@proj-airi/stage-ui/stores/modules/airi-card'
 import { storeToRefs } from 'pinia'
@@ -84,7 +86,7 @@ function handleActivate() {
 }
 
 function highlightTagToHtml(text: string) {
-  return text?.replace(/\{\{(.*?)\}\}/g, '<span class="bg-primary-500/20 inline-block">{{ $1 }}</span>').trim()
+  return DOMPurify.sanitize(text?.replace(/\{\{(.*?)\}\}/g, '<span class="bg-primary-500/20 inline-block">{{ $1 }}</span>').trim())
 }
 
 // Delete confirmation
diff --git a/apps/stage-tamagotchi/package.json b/apps/stage-tamagotchi/package.json
index 0227eb082..d46b65b7a 100644
--- a/apps/stage-tamagotchi/package.json
+++ b/apps/stage-tamagotchi/package.json
@@ -56,6 +56,7 @@
     "colorjs.io": "^0.5.2",
     "culori": "^4.0.2",
     "date-fns": "^4.1.0",
+    "dompurify": "^3.2.6",
     "drizzle-kit": "^0.31.4",
     "drizzle-orm": "^0.44.5",
     "jszip": "^3.10.1",
diff --git a/apps/stage-tamagotchi/src/pages/settings/airi-card/components/CardDetailDialog.vue b/apps/stage-tamagotchi/src/pages/settings/airi-card/components/CardDetailDialog.vue
index 364714e86..a904406d2 100644
--- a/apps/stage-tamagotchi/src/pages/settings/airi-card/components/CardDetailDialog.vue
+++ b/apps/stage-tamagotchi/src/pages/settings/airi-card/components/CardDetailDialog.vue
@@ -1,6 +1,8 @@
 <script setup lang="ts">
 import type { AiriCard } from '@proj-airi/stage-ui/stores/modules/airi-card'
 
+import DOMPurify from 'dompurify'
+
 import { Button } from '@proj-airi/stage-ui/components'
 import { useAiriCardStore } from '@proj-airi/stage-ui/stores/modules/airi-card'
 import { storeToRefs } from 'pinia'
@@ -84,7 +86,7 @@ function handleActivate() {
 }
 
 function highlightTagToHtml(text: string) {
-  return text?.replace(/\{\{(.*?)\}\}/g, '<span class="bg-primary-500/20 inline-block">{{ $1 }}</span>').trim()
+  return DOMPurify.sanitize(text?.replace(/\{\{(.*?)\}\}/g, '<span class="bg-primary-500/20 inline-block">{{ $1 }}</span>').trim())
 }
 
 // Delete confirmation
diff --git a/apps/stage-web/package.json b/apps/stage-web/package.json
index dc717c790..6f7f3be5b 100644
--- a/apps/stage-web/package.json
+++ b/apps/stage-web/package.json
@@ -55,6 +55,7 @@
     "colorjs.io": "^0.5.2",
     "culori": "^4.0.2",
     "date-fns": "^4.1.0",
+    "dompurify": "^3.2.6",
     "driver.js": "^1.3.6",
     "drizzle-kit": "^0.31.4",
     "drizzle-orm": "^0.44.5",
diff --git a/apps/stage-web/src/pages/settings/airi-card/components/CardDetailDialog.vue b/apps/stage-web/src/pages/settings/airi-card/components/CardDetailDialog.vue
index 364714e86..a904406d2 100644
--- a/apps/stage-web/src/pages/settings/airi-card/components/CardDetailDialog.vue
+++ b/apps/stage-web/src/pages/settings/airi-card/components/CardDetailDialog.vue
@@ -1,6 +1,8 @@
 <script setup lang="ts">
 import type { AiriCard } from '@proj-airi/stage-ui/stores/modules/airi-card'
 
+import DOMPurify from 'dompurify'
+
 import { Button } from '@proj-airi/stage-ui/components'
 import { useAiriCardStore } from '@proj-airi/stage-ui/stores/modules/airi-card'
 import { storeToRefs } from 'pinia'
@@ -84,7 +86,7 @@ function handleActivate() {
 }
 
 function highlightTagToHtml(text: string) {
-  return text?.replace(/\{\{(.*?)\}\}/g, '<span class="bg-primary-500/20 inline-block">{{ $1 }}</span>').trim()
+  return DOMPurify.sanitize(text?.replace(/\{\{(.*?)\}\}/g, '<span class="bg-primary-500/20 inline-block">{{ $1 }}</span>').trim())
 }
 
 // Delete confirmation
diff --git a/cspell.config.yaml b/cspell.config.yaml
index e7ca50175..c3595b1e7 100644
--- a/cspell.config.yaml
+++ b/cspell.config.yaml
@@ -71,6 +71,7 @@ words:
   - devlogs
   - directml
   - dokidoki
+  - dompurify
   - dotenvx
   - DownloadLive2DSDK
   - dreamlog
diff --git a/packages/stage-ui/package.json b/packages/stage-ui/package.json
index 23b4c5e17..6cd6e95c5 100644
--- a/packages/stage-ui/package.json
+++ b/packages/stage-ui/package.json
@@ -93,6 +93,7 @@
     "animejs": "^4.1.3",
     "culori": "^4.0.2",
     "date-fns": "^4.1.0",
+    "dompurify": "^3.2.6",
     "gpuu": "^1.0.4",
     "jszip": "^3.10.1",
     "localforage": "^1.10.0",
diff --git a/packages/stage-ui/src/components/MarkdownRenderer.vue b/packages/stage-ui/src/components/MarkdownRenderer.vue
index 19a58a60d..5847c9493 100644
--- a/packages/stage-ui/src/components/MarkdownRenderer.vue
+++ b/packages/stage-ui/src/components/MarkdownRenderer.vue
@@ -1,4 +1,6 @@
 <script setup lang="ts">
+import DOMPurify from 'dompurify'
+
 import { onMounted, ref, watch } from 'vue'
 
 import { useMarkdown } from '../composables/markdown'
@@ -20,11 +22,11 @@ async function processContent() {
   }
 
   try {
-    processedContent.value = await process(props.content)
+    processedContent.value = DOMPurify.sanitize(await process(props.content))
   }
   catch (error) {
     console.warn('Failed to process markdown with syntax highlighting, using fallback:', error)
-    processedContent.value = processSync(props.content)
+    processedContent.value = DOMPurify.sanitize(processSync(props.content))
   }
 }
 
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 813ab01a9..9c3c00b67 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -284,7 +284,7 @@ importers:
         version: rolldown-vite@7.1.5(@types/node@24.3.0)(esbuild@0.25.9)(jiti@2.5.1)(less@4.4.1)(terser@5.43.1)(tsx@4.20.5)(yaml@2.8.1)
       vite-plugin-vue-devtools:
         specifier: ^8.0.1
-        version: 8.0.1(@nuxt/kit@4.0.3(magicast@0.3.5))(rolldown-vite@7.1.5(@types/node@24.3.0)(esbuild@0.25.9)(jiti@2.5.1)(less@4.4.1)(terser@5.43.1)(tsx@4.20.5)(yaml@2.8.1))(vue@3.5.21(typescript@5.9.2))
+        version: 8.0.1(rolldown-vite@7.1.5(@types/node@24.3.0)(esbuild@0.25.9)(jiti@2.5.1)(less@4.4.1)(terser@5.43.1)(tsx@4.20.5)(yaml@2.8.1))(vue@3.5.21(typescript@5.9.2))
       vite-plugin-vue-layouts:
         specifier: ^0.11.0
         version: 0.11.0(rolldown-vite@7.1.5(@types/node@24.3.0)(esbuild@0.25.9)(jiti@2.5.1)(less@4.4.1)(terser@5.43.1)(tsx@4.20.5)(yaml@2.8.1))(vue-router@4.5.1(vue@3.5.21(typescript@5.9.2)))(vue@3.5.21(typescript@5.9.2))
@@ -454,6 +454,9 @@ importers:
       date-fns:
         specifier: ^4.1.0
         version: 4.1.0
+      dompurify:
+        specifier: ^3.2.6
+        version: 3.2.6
       drizzle-kit:
         specifier: ^0.31.4
         version: 0.31.4
@@ -1164,6 +1167,9 @@ importers:
       date-fns:
         specifier: ^4.1.0
         version: 4.1.0
+      dompurify:
+        specifier: ^3.2.6
+        version: 3.2.6
       driver.js:
         specifier: ^1.3.6
         version: 1.3.6
@@ -1768,6 +1774,9 @@ importers:
       date-fns:
         specifier: ^4.1.0
         version: 4.1.0
+      dompurify:
+        specifier: ^3.2.6
+        version: 3.2.6
       gpuu:
         specifier: ^1.0.4
         version: 1.0.4
@@ -2023,7 +2032,7 @@ importers:
         version: rolldown-vite@7.1.5(@types/node@24.3.0)(esbuild@0.25.9)(jiti@2.5.1)(less@4.4.1)(terser@5.43.1)(tsx@4.20.5)(yaml@2.8.1)
       vite-plugin-vue-devtools:
         specifier: ^8.0.1
-        version: 8.0.1(@nuxt/kit@4.0.3(magicast@0.3.5))(rolldown-vite@7.1.5(@types/node@24.3.0)(esbuild@0.25.9)(jiti@2.5.1)(less@4.4.1)(terser@5.43.1)(tsx@4.20.5)(yaml@2.8.1))(vue@3.5.21(typescript@5.9.2))
+        version: 8.0.1(rolldown-vite@7.1.5(@types/node@24.3.0)(esbuild@0.25.9)(jiti@2.5.1)(less@4.4.1)(terser@5.43.1)(tsx@4.20.5)(yaml@2.8.1))(vue@3.5.21(typescript@5.9.2))
       vue-router:
         specifier: ^4.5.1
         version: 4.5.1(vue@3.5.21(typescript@5.9.2))
@@ -2057,7 +2066,7 @@ importers:
         version: rolldown-vite@7.1.5(@types/node@24.3.0)(esbuild@0.25.9)(jiti@2.5.1)(less@4.4.1)(terser@5.43.1)(tsx@4.20.5)(yaml@2.8.1)
       vite-plugin-vue-devtools:
         specifier: ^8.0.1
-        version: 8.0.1(@nuxt/kit@4.0.3(magicast@0.3.5))(rolldown-vite@7.1.5(@types/node@24.3.0)(esbuild@0.25.9)(jiti@2.5.1)(less@4.4.1)(terser@5.43.1)(tsx@4.20.5)(yaml@2.8.1))(vue@3.5.21(typescript@5.9.2))
+        version: 8.0.1(rolldown-vite@7.1.5(@types/node@24.3.0)(esbuild@0.25.9)(jiti@2.5.1)(less@4.4.1)(terser@5.43.1)(tsx@4.20.5)(yaml@2.8.1))(vue@3.5.21(typescript@5.9.2))
       vue-router:
         specifier: ^4.5.1
         version: 4.5.1(vue@3.5.21(typescript@5.9.2))
@@ -9588,6 +9597,9 @@ packages:
     resolution: {integrity: sha512-cgwlv/1iFQiFnU96XXgROh8xTeetsnJiDsTc7TYCLFd9+/WNkIqPTxiM/8pSd8VIrhXGTf1Ny1q1hquVqDJB5w==}
     engines: {node: '>= 4'}
 
+  dompurify@3.2.6:
+    resolution: {integrity: sha512-/2GogDQlohXPZe6D6NOgQvXLPSYBqIWMnZ8zzOhn09REE4eyAzb+Hed3jhoM9OkuaJ8P6ZGTTVWQKAi8ieIzfQ==}
+
   domutils@2.8.0:
     resolution: {integrity: sha512-w96Cjofp72M5IIhpjgobBimYEfoPjx1Vx0BSX9P30WBdZW2WIKU0T1Bd0kz2eNZ9ikjKgHbEyKx8BB6H1L3h3A==}
 
@@ -25071,6 +25083,10 @@ snapshots:
     dependencies:
       domelementtype: 2.3.0
 
+  dompurify@3.2.6:
+    optionalDependencies:
+      '@types/trusted-types': 2.0.7
+
   domutils@2.8.0:
     dependencies:
       dom-serializer: 1.4.1
@@ -33075,6 +33091,21 @@ snapshots:
       - supports-color
       - vue
 
+  vite-plugin-vue-devtools@8.0.1(rolldown-vite@7.1.5(@types/node@24.3.0)(esbuild@0.25.9)(jiti@2.5.1)(less@4.4.1)(terser@5.43.1)(tsx@4.20.5)(yaml@2.8.1))(vue@3.5.21(typescript@5.9.2)):
+    dependencies:
+      '@vue/devtools-core': 8.0.1(rolldown-vite@7.1.5(@types/node@24.3.0)(esbuild@0.25.9)(jiti@2.5.1)(less@4.4.1)(terser@5.43.1)(tsx@4.20.5)(yaml@2.8.1))(vue@3.5.21(typescript@5.9.2))
+      '@vue/devtools-kit': 8.0.1
+      '@vue/devtools-shared': 8.0.1
+      execa: 9.6.0
+      sirv: 3.0.1
+      vite: rolldown-vite@7.1.5(@types/node@24.3.0)(esbuild@0.25.9)(jiti@2.5.1)(less@4.4.1)(terser@5.43.1)(tsx@4.20.5)(yaml@2.8.1)
+      vite-plugin-inspect: 11.3.3(@nuxt/kit@3.18.1(magicast@0.3.5))(rolldown-vite@7.1.5(@types/node@24.3.0)(esbuild@0.25.9)(jiti@2.5.1)(less@4.4.1)(terser@5.43.1)(tsx@4.20.5)(yaml@2.8.1))
+      vite-plugin-vue-inspector: 5.3.2(rolldown-vite@7.1.5(@types/node@24.3.0)(esbuild@0.25.9)(jiti@2.5.1)(less@4.4.1)(terser@5.43.1)(tsx@4.20.5)(yaml@2.8.1))
+    transitivePeerDependencies:
+      - '@nuxt/kit'
+      - supports-color
+      - vue
+
   vite-plugin-vue-inspector@5.3.2(rolldown-vite@7.1.5(@types/node@24.3.0)(esbuild@0.25.9)(jiti@2.5.1)(less@4.4.1)(terser@5.43.1)(tsx@4.20.5)(yaml@2.8.1)):
     dependencies:
       '@babel/core': 7.28.3