diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1abcdb4a8c3..fc5e5934250 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ Docs: https://docs.openclaw.ai
 ### Fixes
 
 - Security/Voice Call: harden Twilio webhook replay handling by preserving provider event IDs through normalization, adding bounded replay dedupe, and enforcing per-call turn-token matching for call-state transitions. This ships in the next npm release. Thanks @jiseoung for reporting.
+- Security/Export session HTML: escape raw HTML markdown tokens in the exported session viewer, harden tree/header metadata rendering against HTML injection, and sanitize image data-URL MIME types in export output to prevent stored XSS when opening exported HTML files. This ships in the next npm release. Thanks @allsmog for reporting.
 - Security/Commands: enforce sender-only matching for `commands.allowFrom` by blocking conversation-shaped `From` identities (`channel:`, `group:`, `thread:`, `@g.us`) while preserving direct-message fallback when sender fields are missing. Ships in the next npm release. Thanks @jiseoung.
 - Config/Kilo Gateway: Kilo provider flow now surfaces an updated list of models. (#24921) thanks @gumadeiras.
 - Security/Sandbox: enforce `tools.exec.applyPatch.workspaceOnly` and `tools.fs.workspaceOnly` for `apply_patch` in sandbox-mounted paths so writes/deletes cannot escape the workspace boundary via mounts like `/agent` unless explicitly opted out (`tools.exec.applyPatch.workspaceOnly=false`). This ships in the next npm release. Thanks @tdjackey for reporting.
diff --git a/src/auto-reply/reply/export-html/template.js b/src/auto-reply/reply/export-html/template.js
index f4f19a6d25d..318751fde53 100644
--- a/src/auto-reply/reply/export-html/template.js
+++ b/src/auto-reply/reply/export-html/template.js
@@ -665,6 +665,15 @@
     return div.innerHTML;
   }
 
+  // Validate image MIME type to prevent attribute injection in data-URL src.
+  const SAFE_IMAGE_MIME_RE = /^image\/(png|jpeg|gif|webp|svg\+xml|bmp|tiff|avif)$/i;
+  function sanitizeImageMimeType(mimeType) {
+    if (typeof mimeType === "string" && SAFE_IMAGE_MIME_RE.test(mimeType)) {
+      return mimeType;
+    }
+    return "application/octet-stream";
+  }
+
   /**
    * Truncate string to maxLen chars, append "..." if truncated.
    */
@@ -722,13 +731,13 @@
               `<span class="tree-role-tool">${escapeHtml(formatToolCall(toolCall.name, toolCall.arguments))}</span>`
             );
           }
-          return labelHtml + `<span class="tree-role-tool">[${msg.toolName || "tool"}]</span>`;
+          return labelHtml + `<span class="tree-role-tool">[${escapeHtml(msg.toolName || "tool")}]</span>`;
         }
         if (msg.role === "bashExecution") {
           const cmd = truncate(normalize(msg.command || ""));
           return labelHtml + `<span class="tree-role-tool">[bash]:</span> ${escapeHtml(cmd)}`;
         }
-        return labelHtml + `<span class="tree-muted">[${msg.role}]</span>`;
+        return labelHtml + `<span class="tree-muted">[${escapeHtml(msg.role)}]</span>`;
       }
       case "compaction":
         return (
@@ -751,11 +760,11 @@
         );
       }
       case "model_change":
-        return labelHtml + `<span class="tree-muted">[model: ${entry.modelId}]</span>`;
+        return labelHtml + `<span class="tree-muted">[model: ${escapeHtml(entry.modelId)}]</span>`;
       case "thinking_level_change":
-        return labelHtml + `<span class="tree-muted">[thinking: ${entry.thinkingLevel}]</span>`;
+        return labelHtml + `<span class="tree-muted">[thinking: ${escapeHtml(entry.thinkingLevel)}]</span>`;
       default:
-        return labelHtml + `<span class="tree-muted">[${entry.type}]</span>`;
+        return labelHtml + `<span class="tree-muted">[${escapeHtml(entry.type)}]</span>`;
     }
   }
 
@@ -1029,7 +1038,10 @@
       return (
         '<div class="tool-images">' +
         images
-          .map((img) => `<img src="data:${img.mimeType};base64,${img.data}" class="tool-image" />`)
+          .map(
+            (img) =>
+              `<img src="data:${sanitizeImageMimeType(img.mimeType)};base64,${img.data}" class="tool-image" />`,
+          )
           .join("") +
         "</div>"
       );
@@ -1303,7 +1315,7 @@
           if (images.length > 0) {
             html += '<div class="message-images">';
             for (const img of images) {
-              html += `<img src="data:${img.mimeType};base64,${img.data}" class="message-image" />`;
+              html += `<img src="data:${sanitizeImageMimeType(img.mimeType)};base64,${img.data}" class="message-image" />`;
             }
             html += "</div>";
           }
@@ -1522,7 +1534,7 @@
             </div>
             <div class="header-info">
               <div class="info-item"><span class="info-label">Date:</span><span class="info-value">${header?.timestamp ? new Date(header.timestamp).toLocaleString() : "unknown"}</span></div>
-              <div class="info-item"><span class="info-label">Models:</span><span class="info-value">${globalStats.models.join(", ") || "unknown"}</span></div>
+              <div class="info-item"><span class="info-label">Models:</span><span class="info-value">${escapeHtml(globalStats.models.join(", ") || "unknown")}</span></div>
               <div class="info-item"><span class="info-label">Messages:</span><span class="info-value">${msgParts.join(", ") || "0"}</span></div>
               <div class="info-item"><span class="info-label">Tool Calls:</span><span class="info-value">${globalStats.toolCalls}</span></div>
               <div class="info-item"><span class="info-label">Tokens:</span><span class="info-value">${tokenParts.join(" ") || "0"}</span></div>
@@ -1718,6 +1730,10 @@
       codespan(token) {
         return `<code>${escapeHtml(token.text)}</code>`;
       },
+      // Raw HTML blocks/inline HTML: escape to prevent script execution.
+      html(token) {
+        return escapeHtml(token.text);
+      },
     },
   });
 
diff --git a/src/auto-reply/reply/export-html/template.security.test.ts b/src/auto-reply/reply/export-html/template.security.test.ts
new file mode 100644
index 00000000000..2837df7036b
--- /dev/null
+++ b/src/auto-reply/reply/export-html/template.security.test.ts
@@ -0,0 +1,253 @@
+import fs from "node:fs";
+import path from "node:path";
+import vm from "node:vm";
+import { fileURLToPath } from "node:url";
+import { describe, expect, it } from "vitest";
+import { parseHTML } from "linkedom";
+
+type SessionEntry = {
+  id: string;
+  parentId: string | null;
+  timestamp: string;
+  type: string;
+  message?: unknown;
+  summary?: string;
+  content?: unknown;
+  display?: boolean;
+  customType?: string;
+  provider?: string;
+  modelId?: string;
+  thinkingLevel?: string;
+};
+
+type SessionData = {
+  header: { id: string; timestamp: string };
+  entries: SessionEntry[];
+  leafId: string;
+  systemPrompt: string;
+  tools: unknown[];
+};
+
+const exportHtmlDir = path.dirname(fileURLToPath(import.meta.url));
+const templateHtml = fs.readFileSync(path.join(exportHtmlDir, "template.html"), "utf8");
+const templateJs = fs.readFileSync(path.join(exportHtmlDir, "template.js"), "utf8");
+const markedJs = fs.readFileSync(path.join(exportHtmlDir, "vendor", "marked.min.js"), "utf8");
+const highlightJs = fs.readFileSync(path.join(exportHtmlDir, "vendor", "highlight.min.js"), "utf8");
+
+function renderTemplate(sessionData: SessionData) {
+  const html = templateHtml
+    .replace("{{CSS}}", "")
+    .replace("{{SESSION_DATA}}", Buffer.from(JSON.stringify(sessionData), "utf8").toString("base64"))
+    .replace("{{MARKED_JS}}", "")
+    .replace("{{HIGHLIGHT_JS}}", "")
+    .replace("{{JS}}", "");
+
+  const { document, window } = parseHTML(html);
+  if (window.HTMLElement?.prototype) {
+    window.HTMLElement.prototype.scrollIntoView = () => {};
+  }
+
+  const immediateTimeout = (fn: (...args: unknown[]) => void) => {
+    fn();
+    return 0;
+  };
+  const runtime: Record<string, unknown> = {
+    document,
+    console,
+    clearTimeout: () => {},
+    setTimeout: immediateTimeout,
+    URLSearchParams,
+    TextDecoder,
+    atob: (s: string) => Buffer.from(s, "base64").toString("binary"),
+    btoa: (s: string) => Buffer.from(s, "binary").toString("base64"),
+    navigator: { clipboard: { writeText: async () => {} } },
+    history: { replaceState: () => {} },
+    location: { href: "http://localhost/export.html", search: "" },
+  };
+  runtime.window = runtime;
+  runtime.self = runtime;
+  runtime.globalThis = runtime;
+
+  vm.createContext(runtime);
+  vm.runInContext(markedJs, runtime);
+  vm.runInContext(highlightJs, runtime);
+  vm.runInContext(templateJs, runtime);
+  return { document };
+}
+
+function now() {
+  return new Date("2026-02-24T00:00:00.000Z").toISOString();
+}
+
+describe("export html security hardening", () => {
+  it("escapes raw HTML from markdown blocks", () => {
+    const attack = "<img src=x onerror=alert(1)>";
+    const session: SessionData = {
+      header: { id: "session-1", timestamp: now() },
+      entries: [
+        {
+          id: "1",
+          parentId: null,
+          timestamp: now(),
+          type: "message",
+          message: { role: "user", content: attack },
+        },
+        {
+          id: "2",
+          parentId: "1",
+          timestamp: now(),
+          type: "branch_summary",
+          summary: attack,
+        },
+        {
+          id: "3",
+          parentId: "2",
+          timestamp: now(),
+          type: "custom_message",
+          customType: "x",
+          display: true,
+          content: attack,
+        },
+      ],
+      leafId: "3",
+      systemPrompt: "",
+      tools: [],
+    };
+
+    const { document } = renderTemplate(session);
+    const messages = document.getElementById("messages");
+    expect(messages).toBeTruthy();
+    expect(messages?.querySelector("img[onerror]")).toBeNull();
+    expect(messages?.innerHTML).toContain("&lt;img src=x onerror=alert(1)&gt;");
+  });
+
+  it("escapes tree and header metadata fields", () => {
+    const attack = "<img src=x onerror=alert(9)>";
+    const baseEntries: SessionEntry[] = [
+      {
+        id: "1",
+        parentId: null,
+        timestamp: now(),
+        type: "message",
+        message: { role: "user", content: "ok" },
+      },
+      {
+        id: "2",
+        parentId: "1",
+        timestamp: now(),
+        type: "message",
+        message: {
+          role: "assistant",
+          model: attack,
+          provider: "p",
+          content: [{ type: "text", text: "assistant" }],
+        },
+      },
+      {
+        id: "3",
+        parentId: "2",
+        timestamp: now(),
+        type: "message",
+        message: { role: "toolResult", toolName: attack },
+      },
+      {
+        id: "4",
+        parentId: "3",
+        timestamp: now(),
+        type: "model_change",
+        provider: "p",
+        modelId: attack,
+      },
+      {
+        id: "5",
+        parentId: "4",
+        timestamp: now(),
+        type: "thinking_level_change",
+        thinkingLevel: attack,
+      },
+      {
+        id: "6",
+        parentId: "5",
+        timestamp: now(),
+        type: attack,
+      },
+    ];
+
+    const headerSession: SessionData = {
+      header: { id: "session-2", timestamp: now() },
+      entries: baseEntries,
+      leafId: "6",
+      systemPrompt: "",
+      tools: [],
+    };
+
+    const { document } = renderTemplate(headerSession);
+    const tree = document.getElementById("tree-container");
+    const header = document.getElementById("header-container");
+    expect(tree).toBeTruthy();
+    expect(header).toBeTruthy();
+    expect(tree?.querySelector("img[onerror]")).toBeNull();
+    expect(header?.querySelector("img[onerror]")).toBeNull();
+    expect(tree?.innerHTML).toContain("&lt;img src=x onerror=alert(9)&gt;");
+    expect(header?.innerHTML).toContain("&lt;img src=x onerror=alert(9)&gt;");
+
+    const modelLeafSession: SessionData = {
+      header: { id: "session-2-model", timestamp: now() },
+      entries: baseEntries,
+      leafId: "4",
+      systemPrompt: "",
+      tools: [],
+    };
+    const modelLeaf = renderTemplate(modelLeafSession).document;
+    expect(modelLeaf.getElementById("tree-container")?.querySelector("img[onerror]")).toBeNull();
+    expect(modelLeaf.getElementById("tree-container")?.innerHTML).toContain(
+      "&lt;img src=x onerror=alert(9)&gt;",
+    );
+
+    const thinkingLeafSession: SessionData = {
+      header: { id: "session-2-thinking", timestamp: now() },
+      entries: baseEntries,
+      leafId: "5",
+      systemPrompt: "",
+      tools: [],
+    };
+    const thinkingLeaf = renderTemplate(thinkingLeafSession).document;
+    expect(thinkingLeaf.getElementById("tree-container")?.querySelector("img[onerror]")).toBeNull();
+    expect(thinkingLeaf.getElementById("tree-container")?.innerHTML).toContain(
+      "&lt;img src=x onerror=alert(9)&gt;",
+    );
+  });
+
+  it("sanitizes image MIME types used in data URLs", () => {
+    const session: SessionData = {
+      header: { id: "session-3", timestamp: now() },
+      entries: [
+        {
+          id: "1",
+          parentId: null,
+          timestamp: now(),
+          type: "message",
+          message: {
+            role: "user",
+            content: [
+              {
+                type: "image",
+                data: "AAAA",
+                mimeType: 'image/png" onerror="alert(7)',
+              },
+            ],
+          },
+        },
+      ],
+      leafId: "1",
+      systemPrompt: "",
+      tools: [],
+    };
+
+    const { document } = renderTemplate(session);
+    const img = document.querySelector("#messages .message-image");
+    expect(img).toBeTruthy();
+    expect(img?.getAttribute("onerror")).toBeNull();
+    expect(img?.getAttribute("src")).toBe("data:application/octet-stream;base64,AAAA");
+  });
+});