diff --git a/CHANGELOG.md b/CHANGELOG.md
index 87bc08720b0..7343d47ddc6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@ Docs: https://docs.openclaw.ai
 
 ### Fixes
 
+- Gateway/media: prevent image filenames from overriding generic non-image byte sniffing, so zip/octet-stream payloads mislabeled as images are offloaded or rejected before they become inline image attachments.
 - MS Teams/media: sniff inline `data:image/*` attachment bytes before staging them, skipping payloads that are not actually images.
 - Update: let package-swap `doctor --fix` persist core config repairs while plugin schemas are still converging, preventing update failures on externalized channel configs.
 - Telegram: let authorized text `/stop` commands use the fast-abort path before queued agent work, so active turns stop immediately instead of processing the abort after the turn finishes. Fixes #82162. Thanks @civiltox.
diff --git a/src/gateway/chat-attachments.test.ts b/src/gateway/chat-attachments.test.ts
index 5afa86caf11..47485efebbe 100644
--- a/src/gateway/chat-attachments.test.ts
+++ b/src/gateway/chat-attachments.test.ts
@@ -295,6 +295,23 @@ describe("parseMessageWithAttachments", () => {
     expect(parsed.offloadedRefs[0]?.label).toBe("bundle.zip");
     expect(parsed.offloadedRefs[0]?.mimeType).toBe("application/zip");
   });
+
+  it("does not let image filenames override generic non-image byte sniffing", async () => {
+    const zip = Buffer.from("PK\u0003\u0004zip-archive-bytes").toString("base64");
+    const { parsed, logs } = await parseWithWarnings("x", [
+      {
+        type: "image",
+        mimeType: "image/png",
+        fileName: "fake.png",
+        content: zip,
+      },
+    ]);
+    expect(parsed.images).toHaveLength(0);
+    expect(parsed.offloadedRefs).toHaveLength(1);
+    expect(parsed.offloadedRefs[0]?.mimeType).toBe("application/zip");
+    expect(savedMime()).toBe("application/zip");
+    expect(logs[0]).toMatch(/mime mismatch/i);
+  });
 });
 
 describe("parseMessageWithAttachments validation errors", () => {
@@ -349,6 +366,23 @@ describe("parseMessageWithAttachments validation errors", () => {
     expect(saveMediaBufferMock).not.toHaveBeenCalled();
   });
 
+  it("rejects generic-container payloads with image mime and image filename when acceptNonImage is false", async () => {
+    const zip = Buffer.from("PK\u0003\u0004zip-archive-bytes").toString("base64");
+    let caught: unknown;
+    try {
+      await parseMessageWithAttachments(
+        "x",
+        [{ type: "image", mimeType: "image/png", fileName: "fake.png", content: zip }],
+        { log: { warn: () => {} }, acceptNonImage: false },
+      );
+    } catch (err) {
+      caught = err;
+    }
+    expect(caught).toBeInstanceOf(UnsupportedAttachmentError);
+    expect((caught as UnsupportedAttachmentError).reason).toBe("unsupported-non-image");
+    expect(saveMediaBufferMock).not.toHaveBeenCalled();
+  });
+
   it("throws UnsupportedAttachmentError on image when supportsInlineImages is false", async () => {
     let caught: unknown;
     try {
diff --git a/src/gateway/chat-attachments.ts b/src/gateway/chat-attachments.ts
index a2bb1304649..4c3cf0d02cd 100644
--- a/src/gateway/chat-attachments.ts
+++ b/src/gateway/chat-attachments.ts
@@ -107,11 +107,40 @@ function isGenericContainerMime(mime?: string): boolean {
   return mime === "application/zip" || mime === "application/octet-stream";
 }
 
-function shouldIgnoreProvidedImageMime(params: {
+function shouldIgnoreImageMimeHint(params: { sniffedMime?: string; hintedMime?: string }): boolean {
+  return isGenericContainerMime(params.sniffedMime) && isImageMime(params.hintedMime);
+}
+
+function isSpecificMime(mime?: string): boolean {
+  return Boolean(mime && !isGenericContainerMime(mime));
+}
+
+function resolveAttachmentMime(params: {
   sniffedMime?: string;
   providedMime?: string;
-}): boolean {
-  return isGenericContainerMime(params.sniffedMime) && isImageMime(params.providedMime);
+  labelMime?: string;
+}): string {
+  const trustedProvidedMime = shouldIgnoreImageMimeHint({
+    sniffedMime: params.sniffedMime,
+    hintedMime: params.providedMime,
+  })
+    ? undefined
+    : params.providedMime;
+  const trustedLabelMime = shouldIgnoreImageMimeHint({
+    sniffedMime: params.sniffedMime,
+    hintedMime: params.labelMime,
+  })
+    ? undefined
+    : params.labelMime;
+  return (
+    (isSpecificMime(params.sniffedMime) && params.sniffedMime) ||
+    (isSpecificMime(trustedProvidedMime) && trustedProvidedMime) ||
+    (isSpecificMime(trustedLabelMime) && trustedLabelMime) ||
+    params.sniffedMime ||
+    trustedProvidedMime ||
+    trustedLabelMime ||
+    "application/octet-stream"
+  );
 }
 
 function isValidBase64(value: string): boolean {
@@ -264,24 +293,12 @@ export async function parseMessageWithAttachments(
       const providedMime = normalizeMime(mime);
       const sniffedMime = normalizeMime(await sniffMimeFromBase64(b64));
       const labelMime = normalizeMime(mimeTypeFromFilePath(label));
-      const trustedProvidedMime = shouldIgnoreProvidedImageMime({ sniffedMime, providedMime })
-        ? undefined
-        : providedMime;
 
       // Prefer specific MIME signals over generic container types. OOXML
       // documents (docx/xlsx/pptx) sniff as application/zip; without this
       // priority the agent would receive a `.zip` instead of the specific
       // Office document the caller declared.
-      const finalMime =
-        (sniffedMime && !isGenericContainerMime(sniffedMime) && sniffedMime) ||
-        (trustedProvidedMime &&
-          !isGenericContainerMime(trustedProvidedMime) &&
-          trustedProvidedMime) ||
-        (labelMime && !isGenericContainerMime(labelMime) && labelMime) ||
-        sniffedMime ||
-        trustedProvidedMime ||
-        labelMime ||
-        "application/octet-stream";
+      const finalMime = resolveAttachmentMime({ sniffedMime, providedMime, labelMime });
 
       if (
         sniffedMime &&
diff --git a/src/gateway/server-methods/chat.directive-tags.test.ts b/src/gateway/server-methods/chat.directive-tags.test.ts
index d9a1fa11841..0fa317033bd 100644
--- a/src/gateway/server-methods/chat.directive-tags.test.ts
+++ b/src/gateway/server-methods/chat.directive-tags.test.ts
@@ -2905,6 +2905,62 @@ describe("chat directive tag stripping for non-streaming final payloads", () =>
     expect(mockState.lastDispatchCtx?.MediaStaged).toBe(true);
   });
 
+  it("routes image-named generic container bytes as non-image media paths for chat.send", async () => {
+    createTranscriptFixture("openclaw-chat-send-spoofed-image-container-");
+    mockState.finalText = "ok";
+    mockState.sessionEntry = {
+      modelProvider: "test-provider",
+      model: "vision-model",
+    };
+    mockState.modelCatalog = [
+      {
+        provider: "test-provider",
+        id: "vision-model",
+        name: "Vision model",
+        input: ["text", "image"],
+      },
+    ];
+    mockState.savedMediaResults = [
+      { path: "/home/user/.openclaw/media/inbound/fake.zip", contentType: "application/zip" },
+    ];
+    const respond = vi.fn();
+    const context = createChatContext();
+    const zip = Buffer.from("PK\u0003\u0004zip-archive-bytes").toString("base64");
+
+    await runNonStreamingChatSend({
+      context,
+      respond,
+      idempotencyKey: "idem-spoofed-image-container",
+      message: "inspect this",
+      requestParams: {
+        attachments: [
+          {
+            type: "image",
+            mimeType: "image/png",
+            fileName: "fake.png",
+            content: zip,
+          },
+        ],
+      },
+      expectBroadcast: false,
+    });
+
+    expect(mockState.savedMediaCalls).toEqual([
+      {
+        contentType: "application/zip",
+        subdir: "inbound",
+        size: mockState.savedMediaCalls[0]?.size ?? 0,
+      },
+    ]);
+    expect(mockState.lastDispatchCtx?.MediaPaths).toEqual([
+      "/home/user/.openclaw/media/inbound/fake.zip",
+    ]);
+    expect(mockState.lastDispatchCtx?.MediaTypes).toEqual(["application/zip"]);
+    expect(mockState.lastDispatchImages).toBeUndefined();
+    expect(mockState.lastDispatchCtx?.Body).not.toContain("media://");
+    expect(mockState.lastDispatchCtx?.MediaStaged).toBe(true);
+  });
+
   it("preserves sandbox-relative MediaPaths and stores workspace context for media-understanding", async () => {
     createTranscriptFixture("openclaw-chat-send-non-image-absolutize-");
     mockState.finalText = "ok";