diff --git a/src/web/app.js b/src/web/app.js
index 111ab22..f216da8 100644
--- a/src/web/app.js
+++ b/src/web/app.js
@@ -183,7 +183,7 @@ function renderCombinedCard(pair) {
           <div class="meta">
             <input type="checkbox" class="memory-checkbox" data-id="${memory.id}" ${isSelected ? "checked" : ""} />
             <span class="badge badge-memory">${t("badge-memory")}</span>
-            ${memory.memoryType ? `<span class="badge badge-type">${memory.memoryType}</span>` : ""}
+            ${memory.memoryType ? `<span class="badge badge-type">${escapeHtml(memory.memoryType)}</span>` : ""}
             ${similarityHtml}
             ${isPinned ? `<span class="badge badge-pinned">${t("badge-pinned")}</span>` : ""}
             <span class="memory-display-name">${escapeHtml(memory.displayName || memory.id)}</span>
@@ -281,7 +281,7 @@ function renderMemoryCard(memory) {
       <div class="memory-header">
         <div class="meta">
           <input type="checkbox" class="memory-checkbox" data-id="${memory.id}" ${isSelected ? "checked" : ""} />
-          ${memory.memoryType ? `<span class="badge badge-type">${memory.memoryType}</span>` : ""}
+          ${memory.memoryType ? `<span class="badge badge-type">${escapeHtml(memory.memoryType)}</span>` : ""}
           ${isLinked ? `<span class="badge badge-linked"><i data-lucide="link" class="icon-sm"></i> ${t("badge-linked")}</span>` : ""}
           ${similarityHtml}
           ${isPinned ? `<span class="badge badge-pinned">${t("badge-pinned")}</span>` : ""}
diff --git a/tests/web-memorytype-xss.test.ts b/tests/web-memorytype-xss.test.ts
new file mode 100644
index 0000000..863a1ea
--- /dev/null
+++ b/tests/web-memorytype-xss.test.ts
@@ -0,0 +1,125 @@
+import { describe, expect, it } from "bun:test";
+import { readFileSync } from "node:fs";
+import { Script, createContext } from "node:vm";
+
+type RenderMemoryCard = (memory: MemoryFixture) => string;
+type RenderCombinedCard = (pair: CombinedCardFixture) => string;
+
+type MemoryFixture = {
+  id: string;
+  content: string;
+  memoryType: string;
+  tags: readonly string[];
+  createdAt: string;
+  displayName: string;
+  isPinned: boolean;
+};
+
+type PromptFixture = {
+  id: string;
+  content: string;
+  createdAt: string;
+};
+
+type CombinedCardFixture = {
+  memory: MemoryFixture;
+  prompt: PromptFixture;
+};
+
+type RenderHarness = {
+  renderMemoryCard: RenderMemoryCard;
+  renderCombinedCard: RenderCombinedCard;
+};
+
+const MALICIOUS_MEMORY_TYPE = '</span><img src=x onerror="window.__xssFired=true"><span>';
+
+function loadRenderHarness(): RenderHarness {
+  const source = readFileSync(new URL("../src/web/app.js", import.meta.url), "utf-8");
+  const context = createContext({
+    console,
+    DOMPurify: { sanitize: (html: string) => html },
+    getLanguage: () => "en",
+    lucide: { createIcons: () => undefined },
+    marked: { parse: (markdown: string) => markdown, setOptions: () => undefined },
+    t: (key: string) => key,
+    document: {
+      addEventListener: () => undefined,
+      createElement: () => {
+        let text = "";
+        return {
+          set textContent(value: string) {
+            text = value;
+          },
+          get innerHTML() {
+            return text
+              .replace(/&/g, "&amp;")
+              .replace(/</g, "&lt;")
+              .replace(/>/g, "&gt;")
+              .replace(/\"/g, "&quot;")
+              .replace(/'/g, "&#039;");
+          },
+        };
+      },
+    },
+  });
+
+  new Script(
+    `${source}\n;globalThis.__renderMemoryCard = renderMemoryCard;\n;globalThis.__renderCombinedCard = renderCombinedCard;`
+  ).runInContext(context);
+
+  return {
+    renderMemoryCard: context.__renderMemoryCard as RenderMemoryCard,
+    renderCombinedCard: context.__renderCombinedCard as RenderCombinedCard,
+  };
+}
+
+function createMemory(): MemoryFixture {
+  return {
+    id: "mem_xss_repro",
+    content: "benign content",
+    memoryType: MALICIOUS_MEMORY_TYPE,
+    tags: [],
+    createdAt: "2026-06-22T20:21:11.419Z",
+    displayName: "XSS repro memory",
+    isPinned: false,
+  };
+}
+
+function expectEscapedMemoryType(html: string): void {
+  expect(html).not.toContain("<img src=x");
+  expect(html).not.toContain('onerror="');
+  expect(html).toContain("&lt;/span&gt;&lt;img src=x");
+}
+
+describe("web memoryType rendering", () => {
+  it("escapes memoryType in standalone memory cards", () => {
+    // Given: a stored memory with an HTML event-handler payload in memoryType.
+    const { renderMemoryCard } = loadRenderHarness();
+    const memory = createMemory();
+
+    // When: the Web UI renders the standalone memory card.
+    const html = renderMemoryCard(memory);
+
+    // Then: the payload is displayed as badge text, not parsed as executable HTML.
+    expectEscapedMemoryType(html);
+  });
+
+  it("escapes memoryType in combined prompt-memory cards", () => {
+    // Given: a stored memory linked to a prompt with an HTML payload in memoryType.
+    const { renderCombinedCard } = loadRenderHarness();
+    const memory = createMemory();
+
+    // When: the Web UI renders the combined prompt-memory card.
+    const html = renderCombinedCard({
+      memory,
+      prompt: {
+        id: "prompt_xss_repro",
+        content: "remember this",
+        createdAt: "2026-06-22T20:20:00.000Z",
+      },
+    });
+
+    // Then: the payload is displayed as badge text, not parsed as executable HTML.
+    expectEscapedMemoryType(html);
+  });
+});