LINE: harden Express webhook parsing to verified raw body (#51202)

* LINE: enforce signed-raw webhook parsing

* LINE: narrow scope and add buffer regression

* changelog

Signed-off-by: joshavant <830519+joshavant@users.noreply.github.com>

---------

Signed-off-by: joshavant <830519+joshavant@users.noreply.github.com>

CHANGELOG.md

@@ -152,6 +152,7 @@ Docs: https://docs.openclaw.ai
 - Telegram: stabilize pairing/session/forum routing and reply formatting tests (#50155) Thanks @joshavant.
 - Hardening: refresh stale device pairing requests and pending metadata (#50695) Thanks @smaeljaish771 and @joshavant.
 - Gateway: harden OpenResponses file-context escaping (#50782) Thanks @YLChen-007 and @joshavant.
+- LINE: harden Express webhook parsing to verified raw body (#51202) Thanks @gladiator9797 and @joshavant.
 - xAI/models: rename the bundled Grok 4.20 catalog entries to the GA IDs and normalize saved deprecated beta IDs at runtime so existing configs and sessions keep resolving. (#50772) thanks @Jaaneek
 
 ### Fixes

docs/channels/line.md

@@ -51,6 +51,7 @@ If you need a custom path, set `channels.line.webhookPath` or
 Security note:
 
 - LINE signature verification is body-dependent (HMAC over the raw body), so OpenClaw applies strict pre-auth body limits and timeout before verification.
+- OpenClaw processes webhook events from the verified raw request bytes. Upstream middleware-transformed `req.body` values are ignored for signature-integrity safety.
 
 ## Configure
 

src/line/webhook.test.ts

@@ -138,6 +138,92 @@ describe("createLineWebhookMiddleware", () => {
     expect(onEvents).not.toHaveBeenCalled();
   });
 
+  it("uses the signed raw body instead of a pre-parsed req.body object", async () => {
+    const onEvents = vi.fn(async (_body: WebhookRequestBody) => {});
+    const rawBody = JSON.stringify({
+      events: [{ type: "message", source: { userId: "signed-user" } }],
+    });
+    const reqBody = {
+      events: [{ type: "message", source: { userId: "tampered-user" } }],
+    };
+    const middleware = createLineWebhookMiddleware({
+      channelSecret: SECRET,
+      onEvents,
+    });
+
+    const req = {
+      headers: { "x-line-signature": sign(rawBody, SECRET) },
+      rawBody,
+      body: reqBody,
+      // oxlint-disable-next-line typescript/no-explicit-any
+    } as any;
+    const res = createRes();
+
+    // oxlint-disable-next-line typescript/no-explicit-any
+    await middleware(req, res, {} as any);
+
+    expect(res.status).toHaveBeenCalledWith(200);
+    expect(onEvents).toHaveBeenCalledTimes(1);
+    const processedBody = onEvents.mock.calls[0]?.[0] as WebhookRequestBody | undefined;
+    expect(processedBody?.events?.[0]?.source?.userId).toBe("signed-user");
+    expect(processedBody?.events?.[0]?.source?.userId).not.toBe("tampered-user");
+  });
+
+  it("uses signed raw buffer body instead of a pre-parsed req.body object", async () => {
+    const onEvents = vi.fn(async (_body: WebhookRequestBody) => {});
+    const rawBodyText = JSON.stringify({
+      events: [{ type: "message", source: { userId: "signed-buffer-user" } }],
+    });
+    const reqBody = {
+      events: [{ type: "message", source: { userId: "tampered-user" } }],
+    };
+    const middleware = createLineWebhookMiddleware({
+      channelSecret: SECRET,
+      onEvents,
+    });
+
+    const req = {
+      headers: { "x-line-signature": sign(rawBodyText, SECRET) },
+      rawBody: Buffer.from(rawBodyText, "utf-8"),
+      body: reqBody,
+      // oxlint-disable-next-line typescript/no-explicit-any
+    } as any;
+    const res = createRes();
+
+    // oxlint-disable-next-line typescript/no-explicit-any
+    await middleware(req, res, {} as any);
+
+    expect(res.status).toHaveBeenCalledWith(200);
+    expect(onEvents).toHaveBeenCalledTimes(1);
+    const processedBody = onEvents.mock.calls[0]?.[0] as WebhookRequestBody | undefined;
+    expect(processedBody?.events?.[0]?.source?.userId).toBe("signed-buffer-user");
+    expect(processedBody?.events?.[0]?.source?.userId).not.toBe("tampered-user");
+  });
+
+  it("rejects invalid signed raw JSON even when req.body is a valid object", async () => {
+    const onEvents = vi.fn(async (_body: WebhookRequestBody) => {});
+    const rawBody = "not-json";
+    const middleware = createLineWebhookMiddleware({
+      channelSecret: SECRET,
+      onEvents,
+    });
+
+    const req = {
+      headers: { "x-line-signature": sign(rawBody, SECRET) },
+      rawBody,
+      body: { events: [{ type: "message" }] },
+      // oxlint-disable-next-line typescript/no-explicit-any
+    } as any;
+    const res = createRes();
+
+    // oxlint-disable-next-line typescript/no-explicit-any
+    await middleware(req, res, {} as any);
+
+    expect(res.status).toHaveBeenCalledWith(400);
+    expect(res.json).toHaveBeenCalledWith({ error: "Invalid webhook payload" });
+    expect(onEvents).not.toHaveBeenCalled();
+  });
+
   it("returns 500 when event processing fails and does not acknowledge with 200", async () => {
     const onEvents = vi.fn(async () => {
       throw new Error("boom");

src/line/webhook.ts

@@ -23,10 +23,7 @@ function readRawBody(req: Request): string | null {
   return Buffer.isBuffer(rawBody) ? rawBody.toString("utf-8") : rawBody;
 }
 
-function parseWebhookBody(req: Request, rawBody?: string | null): WebhookRequestBody | null {
-  if (req.body && typeof req.body === "object" && !Buffer.isBuffer(req.body)) {
-    return req.body as WebhookRequestBody;
-  }
+function parseWebhookBody(rawBody?: string | null): WebhookRequestBody | null {
   if (!rawBody) {
     return null;
   }
@@ -64,7 +61,8 @@ export function createLineWebhookMiddleware(
         return;
       }
 
-      const body = parseWebhookBody(req, rawBody);
+      // Keep processing tied to the exact bytes that passed signature verification.
+      const body = parseWebhookBody(rawBody);
 
       if (!body) {
         res.status(400).json({ error: "Invalid webhook payload" });