OneUptime is a solution for monitoring and managing online services. Prior to version 10.0.34, the WhatsApp POST webhook handler (/notification/whatsapp/webhook) processes incoming status update events without verifying the Meta/WhatsApp X-Hub-Signature-256 HMAC signature, allowing any unauthenticated attacker to send forged webhook payloads that manipulate notification delivery status records, suppress alerts, and corrupt audit trails. The codebase already implements proper signature verification for Slack webhooks. This issue has been patched in version 10.0.34.

Affected: npm: oneuptime

### Summary

The WhatsApp POST webhook handler (`/notification/whatsapp/webhook`) processes incoming status update events without verifying the Meta/WhatsApp `X-Hub-Signature-256` HMAC signature, allowing any unauthenticated attacker to send forged webhook payloads that manipulate notification delivery status records, suppress alerts, and corrupt audit trails. The codebase already implements proper signature verification for Slack webhooks.

### Details

**Vulnerable code — `App/FeatureSet/Notification/API/WhatsApp.ts` lines 372-430:** ```typescript router.post( "/webhook", async (req: ExpressRequest, res: ExpressResponse, next: NextFunction) => { try { const body: JSONObject = req.body as JSONObject; // NO signature verification! No X-Hub-Signature-256 check!

if ( (body["object"] as string | undefined) !== "whatsapp_business_account" ) { return Response.sendEmptySuccessResponse(req, res); }

const entries: JSONArray | undefined = body["entry"] as JSONArray | undefined; // ... processes entries and updates WhatsApp log status records ```

Compare with the Slack webhook which correctly validates signatures:

**`Common/Server/Middleware/SlackAuthorization.ts` line 58:** ```typescript const isValid = crypto.timingSafeEqual( Buffer.from(computedSignature), Buffer.from(slackSignature) ); ```

The WhatsApp GET webhook correctly validates the verify token — only the POST handler (which processes actual event…