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. From 3.5.1 until 3.9.2, an authenticated admin or superadmin can set matchMethod to regex and place a malicious expression in the expectedValue field for advanced HTTP monitor matching. server/src/api/validation/monitorValidation.ts accepts the expression, and server/src/service/network/AdvancedMatcher.ts synchronously evaluates it against an attacker-controlled HTTP response body on the Node.js main event loop without a timeout or worker isolation, allowing catastrophic backtracking to freeze API endpoints, monitor checks, and WebSocket connections for all users. This issue is fixed in version 3.9.2.

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History

Fri, 21 Aug 2026 19:45:00 +0000

Type Values Removed Values Added
First Time appeared Bluewave-labs
Bluewave-labs checkmate
Vendors & Products Bluewave-labs
Bluewave-labs checkmate

Fri, 21 Aug 2026 18:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 21 Aug 2026 18:15:00 +0000

Type Values Removed Values 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. From 3.5.1 until 3.9.2, an authenticated admin or superadmin can set matchMethod to regex and place a malicious expression in the expectedValue field for advanced HTTP monitor matching. server/src/api/validation/monitorValidation.ts accepts the expression, and server/src/service/network/AdvancedMatcher.ts synchronously evaluates it against an attacker-controlled HTTP response body on the Node.js main event loop without a timeout or worker isolation, allowing catastrophic backtracking to freeze API endpoints, monitor checks, and WebSocket connections for all users. This issue is fixed in version 3.9.2.
Title Checkmate: Regular Expression Denial of Service (ReDoS) via User-Controlled Regex in Monitor Advanced Matching
Weaknesses CWE-1333
References
Metrics cvssV3_1

{'score': 4.9, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-08-21T18:07:11.885Z

Reserved: 2026-08-04T21:48:08.612Z

Link: CVE-2026-70656

cve-icon Vulnrichment

Updated: 2026-08-21T18:07:06.659Z

cve-icon NVD

Status : Received

Published: 2026-08-21T18:16:50.277

Modified: 2026-08-21T19:17:50.190

Link: CVE-2026-70656

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-21T20:00:13Z

Weaknesses