CVE-2026-55241
Checkmate: Pre-auth Denial of Service via File Upload on Registration
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.
INFO
Published Date :
Aug. 21, 2026, 6:16 p.m.
Last Modified :
Oct. 14, 2026, 9:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | MITRE-CVE |
Solution
- Update Checkmate to version 3.9.1.
- Apply file size and type limits.
- Validate uploads before processing.
- Restrict concurrent uploads.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-55241.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-55241 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-55241
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-55241 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-55241 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Translated by [email protected]
Oct. 14, 2026
Action Type Old Value New Value Added Translation Title: Checkmate de bluewave-labs, Description: Checkmate es una herramienta de código abierto y autoalojada diseñada para rastrear y monitorear el hardware del servidor, el tiempo de actividad, los tiempos de respuesta y los incidentes en tiempo real con hermosas visualizaciones. Antes de la versión 3.9.1, la ruta pública POST /api/v1/auth/register en server/src/api/routes/authRoutes.ts procesa las cargas multipart de profileImage a través del análisis en memoria de Multer antes de la validación del registro, sin límites de tamaño de archivo, recuento de archivos o tipo MIME en server/src/api/middleware/upload.ts. Un atacante no autenticado puede enviar archivos sobredimensionados concurrentes que se almacenan en búfer antes de que las comprobaciones de registro no válido o de token de invitación rechacen la solicitud, agotando la memoria y provocando la caída o desestabilización del backend. Este problema se solucionó en la versión 3.9.1. -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 25, 2026
Action Type Old Value New Value Added Reference https://github.com/bluewave-labs/Checkmate/security/advisories/GHSA-9xvg-x28f-m78m Added SSVC {'id': 'CVE-2026-55241', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-25T11:47:48.710908Z'} -
New CVE Received by [email protected]
Aug. 21, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'bluewave-labs', 'product': 'Checkmate', 'versions': [{'status': 'affected', 'version': '< 3.9.1'}]}] Added 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-400 Added CWE CWE-770 Added Reference https://github.com/bluewave-labs/Checkmate/commit/091c36cbf338b673110b0806d76df26d52516468 Added Reference https://github.com/bluewave-labs/Checkmate/releases/tag/v3.9.1 Added Reference https://github.com/bluewave-labs/Checkmate/security/advisories/GHSA-9xvg-x28f-m78m