diff --git a/client/src/components/ai/RandomRatingModal.vue b/client/src/components/ai/RandomRatingModal.vue
index c4556a9..f10a1be 100644
--- a/client/src/components/ai/RandomRatingModal.vue
+++ b/client/src/components/ai/RandomRatingModal.vue
@@ -14,7 +14,11 @@
       {{ current.task_title }} · 提交者 {{ current.username }}
     </n-text>
     <div class="preview-wrapper">
-      <iframe class="preview-iframe" :srcdoc="previewContent"></iframe>
+      <iframe
+        class="preview-iframe"
+        :sandbox="PREVIEW_SANDBOX"
+        :srcdoc="previewContent"
+      ></iframe>
     </div>
     <div class="rate-row">
       <n-rate
@@ -38,7 +42,10 @@ import { ref, watch, onUnmounted } from "vue"
 import { useMessage } from "naive-ui"
 import { Submission } from "../../api"
 import { streaming } from "../../store/prompt"
-import { buildPreviewDocument } from "../../utils/previewDocument"
+import {
+  buildPreviewDocument,
+  PREVIEW_SANDBOX,
+} from "../../utils/previewDocument"
 import type { RandomRatingItem } from "../../utils/type"
 
 const message = useMessage()
diff --git a/client/src/components/editor/Preview.vue b/client/src/components/editor/Preview.vue
index 1bab6cc..4316f86 100644
--- a/client/src/components/editor/Preview.vue
+++ b/client/src/components/editor/Preview.vue
@@ -42,7 +42,11 @@
     </n-flex>
   </n-flex>
   <div class="iframe-wrapper" :style="iframeWrapperStyle">
-    <iframe class="iframe" :srcdoc="previewContent"></iframe>
+    <iframe
+      class="iframe"
+      :sandbox="PREVIEW_SANDBOX"
+      :srcdoc="previewContent"
+    ></iframe>
   </div>
 </template>
 <script lang="ts" setup>
@@ -54,7 +58,10 @@ import { submission } from "../../store/submission"
 import { useMessage } from "naive-ui"
 import { Icon } from "@iconify/vue"
 import copy from "copy-text-to-clipboard"
-import { buildPreviewDocument } from "../../utils/previewDocument"
+import {
+  buildPreviewDocument,
+  PREVIEW_SANDBOX,
+} from "../../utils/previewDocument"
 
 interface Props {
   html: string
@@ -145,9 +152,14 @@ function open() {
   } else {
     const newTab = window.open("about:blank", "_blank")
     if (!newTab) return
-    newTab.document.open()
-    newTab.document.write(getContent())
-    newTab.document.close()
+    // 新标签页和本站同源，代码要放进带 sandbox 的 iframe 里跑
+    const doc = newTab.document
+    doc.open()
+    doc.write(
+      `<!DOCTYPE html><title>预览</title><style>html,body,iframe{margin:0;width:100%;height:100%;border:0;display:block}</style><iframe sandbox="${PREVIEW_SANDBOX}"></iframe>`,
+    )
+    doc.close()
+    doc.querySelector("iframe")!.srcdoc = getContent()
   }
 }
 
diff --git a/client/src/components/submissions/ChainModal.vue b/client/src/components/submissions/ChainModal.vue
index bd2f59f..822ee37 100644
--- a/client/src/components/submissions/ChainModal.vue
+++ b/client/src/components/submissions/ChainModal.vue
@@ -240,7 +240,7 @@
 import { computed, ref, watch } from "vue"
 import { NPopconfirm, NButton, useMessage } from "naive-ui"
 import { Icon } from "@iconify/vue"
-import { marked } from "marked"
+import { renderMarkdown } from "../../utils/markdown"
 import { Prompt, Submission } from "../../api"
 import type { PromptRound } from "../../utils/type"
 import { user, roleSuper } from "../../store/user"
@@ -301,10 +301,6 @@ const selectedPageHtml = computed(() => {
   return `<!DOCTYPE html><html><head><meta charset="utf-8">${style}</head><body>${round.html}${script}</body></html>`
 })
 
-function renderMarkdown(text: string): string {
-  return marked.parse(text) as string
-}
-
 function isPromptLong(text: string): boolean {
   return text.length > 220 || text.split(/\r?\n/).length > 4
 }
diff --git a/client/src/pages/Submission.vue b/client/src/pages/Submission.vue
index bf81340..9a5acd2 100644
--- a/client/src/pages/Submission.vue
+++ b/client/src/pages/Submission.vue
@@ -1,39 +1,30 @@
 <script lang="ts" setup>
-import { onMounted, useTemplateRef } from "vue"
+import { onMounted, ref } from "vue"
 import { Submission } from "../api"
 import type { SubmissionAll } from "../utils/type"
-import { buildPreviewDocument } from "../utils/previewDocument"
+import { buildPreviewDocument, PREVIEW_SANDBOX } from "../utils/previewDocument"
 
 interface Props {
   id: string
 }
 const props = defineProps<Props>()
 
-const iframe = useTemplateRef<HTMLIFrameElement>("iframe")
+const content = ref("")
 
 async function init() {
   const submission: SubmissionAll = await Submission.get(props.id)
   Submission.incrementView(props.id)
-
-  if (!iframe.value) return
-  const doc = iframe.value.contentDocument
-  if (doc) {
-    doc.open()
-    doc.write(
-      buildPreviewDocument({
-        html: submission.html,
-        css: submission.css,
-        js: submission.js,
-      }),
-    )
-    doc.close()
-  }
+  content.value = buildPreviewDocument({
+    html: submission.html,
+    css: submission.css,
+    js: submission.js,
+  })
 }
 
 onMounted(init)
 </script>
 <template>
-  <iframe class="iframe" ref="iframe"></iframe>
+  <iframe class="iframe" :sandbox="PREVIEW_SANDBOX" :srcdoc="content"></iframe>
 </template>
 <style scoped>
 .iframe {
diff --git a/client/src/utils/markdown.ts b/client/src/utils/markdown.ts
index e73428b..d153075 100644
--- a/client/src/utils/markdown.ts
+++ b/client/src/utils/markdown.ts
@@ -1,5 +1,33 @@
-import { marked } from "marked"
+import { Marked } from "marked"
+
+// 提示词和 AI 回复是用户可控的内容，渲染进 v-html 前必须去掉可执行的部分：
+// 原始 HTML 一律转义成文本，链接和图片只放行 http(s)/mailto 和相对地址
+const escapeHtml = (s: string) =>
+  s
+    .replace(/&/g, "&amp;")
+    .replace(/</g, "&lt;")
+    .replace(/>/g, "&gt;")
+    .replace(/"/g, "&quot;")
+
+const isSafeUrl = (href: string) =>
+  !/^\s*[a-z][a-z0-9+.-]*:/i.test(href) || /^\s*(https?|mailto):/i.test(href)
+
+const safeMarked = new Marked({
+  renderer: {
+    html({ text }) {
+      return escapeHtml(text)
+    },
+    link({ href, tokens }) {
+      if (isSafeUrl(href)) return false
+      return this.parser.parseInline(tokens)
+    },
+    image({ href, text }) {
+      if (isSafeUrl(href)) return false
+      return escapeHtml(text)
+    },
+  },
+})
 
 export function renderMarkdown(text: string): string {
-  return marked.parse(text) as string
+  return safeMarked.parse(text) as string
 }
diff --git a/client/src/utils/previewDocument.ts b/client/src/utils/previewDocument.ts
index c364a0f..78d30da 100644
--- a/client/src/utils/previewDocument.ts
+++ b/client/src/utils/previewDocument.ts
@@ -1,3 +1,8 @@
+// 预览里跑的是用户写的代码（可能是别人的提交），不能给 allow-same-origin，
+// 否则它和本站同源，能读 localStorage 里的登录 token
+export const PREVIEW_SANDBOX =
+  "allow-scripts allow-modals allow-forms allow-popups allow-pointer-lock"
+
 interface PreviewDocumentOptions {
   html: string
   css: string
diff --git a/server/src/routes/submission.ts b/server/src/routes/submission.ts
index 559bd06..2936b31 100644
--- a/server/src/routes/submission.ts
+++ b/server/src/routes/submission.ts
@@ -530,9 +530,10 @@ router.post("/:id/view", (c) => {
 router.put("/:id/score", async (c) => {
   const user = requireUser(c)
   const id = uuidParam(c, "id")
-  const { score } = await body(c, z.object({ score: z.number().int() }))
+  const { score } = await body(c, z.object({ score: z.number().int().max(5) }))
   if (score <= 0) throw new HttpError(400, "分数不能为零")
-  orNotFound(get(`SELECT 1 FROM submission_submission WHERE id = $id`, { id }))
+  const sub = orNotFound(get<{ user_id: number }>(`SELECT user_id FROM submission_submission WHERE id = $id`, { id }))
+  if (sub.user_id === user.id) throw new HttpError(400, "不能给自己的提交打分")
 
   const exists = get(`SELECT 1 FROM submission_rating WHERE user_id = $user_id AND submission_id = $id`, {
     user_id: user.id,
diff --git a/server/tests/api.test.ts b/server/tests/api.test.ts
index 46ed77c..3e2ad5a 100644
--- a/server/tests/api.test.ts
+++ b/server/tests/api.test.ts
@@ -136,6 +136,10 @@ describe("评分", () => {
     const again = await (await client("s0"))("PUT", `/api/submission/${uuid(sub)}/score`, { score: 1 })
     expect(again.json.message).toBe("你已经给这个提交打过分了")
     expect((await (await client("s0"))("PUT", `/api/submission/${uuid(sub)}/score`, { score: 0 })).status).toBe(400)
+    expect((await (await client("s1"))("PUT", `/api/submission/${uuid(sub)}/score`, { score: 6 })).status).toBe(422)
+    const self = await (await client("author"))("PUT", `/api/submission/${uuid(sub)}/score`, { score: 5 })
+    expect(self.status).toBe(400)
+    expect(all(`SELECT 1 FROM submission_rating WHERE user_id = $id`, { id: author })).toEqual([])
   })
 })