diff --git a/docs/start/openclaw.md b/docs/start/openclaw.md
index 860ab65c44..f35caae6ba 100644
--- a/docs/start/openclaw.md
+++ b/docs/start/openclaw.md
@@ -211,7 +211,7 @@ Outbound attachments from the agent: include `MEDIA:<path-or-url>` on its own li
 
 ```
 Here’s the screenshot.
-MEDIA:/tmp/screenshot.png
+MEDIA:https://example.com/screenshot.png
 ```
 
 OpenClaw extracts these and sends them as media alongside the text.
diff --git a/src/auto-reply/reply.triggers.trigger-handling.stages-inbound-media-into-sandbox-workspace.security.test.ts b/src/auto-reply/reply.triggers.trigger-handling.stages-inbound-media-into-sandbox-workspace.security.test.ts
new file mode 100644
index 0000000000..cd17bb340a
--- /dev/null
+++ b/src/auto-reply/reply.triggers.trigger-handling.stages-inbound-media-into-sandbox-workspace.security.test.ts
@@ -0,0 +1,79 @@
+import fs from "node:fs/promises";
+import { basename, join } from "node:path";
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { withTempHome as withTempHomeBase } from "../../test/helpers/temp-home.js";
+import type { MsgContext, TemplateContext } from "../templating.js";
+
+const sandboxMocks = vi.hoisted(() => ({
+  ensureSandboxWorkspaceForSession: vi.fn(),
+}));
+
+vi.mock("../agents/sandbox.js", () => sandboxMocks);
+
+import { ensureSandboxWorkspaceForSession } from "../agents/sandbox.js";
+import { stageSandboxMedia } from "./reply/stage-sandbox-media.js";
+
+async function withTempHome<T>(fn: (home: string) => Promise<T>): Promise<T> {
+  return withTempHomeBase(async (home) => await fn(home), { prefix: "openclaw-triggers-bypass-" });
+}
+
+afterEach(() => {
+  vi.restoreAllMocks();
+});
+
+describe("stageSandboxMedia security", () => {
+  it("rejects staging host files from outside the media directory", async () => {
+    await withTempHome(async (home) => {
+      // Sensitive host file outside .openclaw
+      const sensitiveFile = join(home, "secrets.txt");
+      await fs.writeFile(sensitiveFile, "SENSITIVE DATA");
+
+      const sandboxDir = join(home, "sandboxes", "session");
+      vi.mocked(ensureSandboxWorkspaceForSession).mockResolvedValue({
+        workspaceDir: sandboxDir,
+        containerWorkdir: "/work",
+      });
+
+      const ctx: MsgContext = {
+        Body: "hi",
+        From: "whatsapp:group:demo",
+        To: "+2000",
+        ChatType: "group",
+        Provider: "whatsapp",
+        MediaPath: sensitiveFile,
+        MediaType: "image/jpeg",
+        MediaUrl: sensitiveFile,
+      };
+      const sessionCtx: TemplateContext = { ...ctx };
+
+      // This should fail or skip the file
+      await stageSandboxMedia({
+        ctx,
+        sessionCtx,
+        cfg: {
+          agents: {
+            defaults: {
+              model: "anthropic/claude-opus-4-5",
+              workspace: join(home, "openclaw"),
+              sandbox: {
+                mode: "non-main",
+                workspaceRoot: join(home, "sandboxes"),
+              },
+            },
+          },
+          channels: { whatsapp: { allowFrom: ["*"] } },
+          session: { store: join(home, "sessions.json") },
+        },
+        sessionKey: "agent:main:main",
+        workspaceDir: join(home, "openclaw"),
+      });
+
+      const stagedFullPath = join(sandboxDir, "media", "inbound", basename(sensitiveFile));
+      // Expect the file NOT to be staged
+      await expect(fs.stat(stagedFullPath)).rejects.toThrow();
+
+      // Context should NOT be rewritten to a sandbox path if it failed to stage
+      expect(ctx.MediaPath).toBe(sensitiveFile);
+    });
+  });
+});
diff --git a/src/auto-reply/reply/get-reply-run.ts b/src/auto-reply/reply/get-reply-run.ts
index 19c4df49b2..d9c7d19cd0 100644
--- a/src/auto-reply/reply/get-reply-run.ts
+++ b/src/auto-reply/reply/get-reply-run.ts
@@ -248,7 +248,7 @@ export async function runPreparedReply(
   const prefixedBody = [threadStarterNote, prefixedBodyBase].filter(Boolean).join("\n\n");
   const mediaNote = buildInboundMediaNote(ctx);
   const mediaReplyHint = mediaNote
-    ? "To send an image back, prefer the message tool (media/path/filePath). If you must inline, use MEDIA:/path or MEDIA:https://example.com/image.jpg (spaces ok, quote if needed). Keep caption in the text body."
+    ? "To send an image back, prefer the message tool (media/path/filePath). If you must inline, use MEDIA:https://example.com/image.jpg (spaces ok, quote if needed) or a safe relative path like MEDIA:./image.jpg. Avoid absolute paths (MEDIA:/...) and ~ paths — they are blocked for security. Keep caption in the text body."
     : undefined;
   let prefixedCommandBody = mediaNote
     ? [mediaNote, mediaReplyHint, prefixedBody ?? ""].filter(Boolean).join("\n").trim()
diff --git a/src/auto-reply/reply/stage-sandbox-media.ts b/src/auto-reply/reply/stage-sandbox-media.ts
index d2a910249e..43d289da5e 100644
--- a/src/auto-reply/reply/stage-sandbox-media.ts
+++ b/src/auto-reply/reply/stage-sandbox-media.ts
@@ -2,9 +2,11 @@ import { spawn } from "node:child_process";
 import fs from "node:fs/promises";
 import path from "node:path";
 import { fileURLToPath } from "node:url";
+import { assertSandboxPath } from "../../agents/sandbox-paths.js";
 import { ensureSandboxWorkspaceForSession } from "../../agents/sandbox.js";
 import type { OpenClawConfig } from "../../config/config.js";
 import { logVerbose } from "../../globals.js";
+import { getMediaDir } from "../../media/store.js";
 import { CONFIG_DIR } from "../../utils.js";
 import type { MsgContext, TemplateContext } from "../templating.js";
 
@@ -80,6 +82,21 @@ export async function stageSandboxMedia(params: {
         continue;
       }
 
+      // Local paths must be restricted to the media directory.
+      if (!ctx.MediaRemoteHost) {
+        const mediaDir = getMediaDir();
+        try {
+          await assertSandboxPath({
+            filePath: source,
+            cwd: mediaDir,
+            root: mediaDir,
+          });
+        } catch {
+          logVerbose(`Blocking attempt to stage media from outside media directory: ${source}`);
+          continue;
+        }
+      }
+
       const baseName = path.basename(source);
       if (!baseName) {
         continue;