Vulnerability · Published Aug 21, 2026 · Assigned by GitHub_M
CVE-2026-55241Checkmate: Pre-auth Denial of Service via File Upload on Registration
High 7.5
In plain English
A high-severity uncontrolled resource consumption in Checkmate from bluewave-labs. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 50% of all known vulnerabilities).
Official description
Checkmate is an open-source, self-hosted tool designed to track and monitor server hardware, uptime, response times, and incidents in real-time with beautiful visualizations. Prior to 3.9.1, the public POST /api/v1/auth/register route in server/src/api/routes/authRoutes.ts passes multipart profileImage uploads through in-memory Multer parsing before registration validation, without file-size, file-count, or MIME-type limits in server/src/api/middleware/upload.ts. An unauthenticated attacker can submit concurrent oversized files that are buffered before invalid registration or invite-token checks reject the request, exhausting memory and crashing or destabilizing the backend. This issue is fixed in version 3.9.1.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| bluewave-labs | Checkmate | < 3.9.1 |
Weakness: CWE-400, CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H