CVE-2026-70656

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.

CVSS Vector

References

• https://github.com/bluewave-labs/Checkmate/commit/0df71d6356c87c747e0b796b0c34e33f2a5203fa
• https://github.com/bluewave-labs/Checkmate/commit/adba25269c455878bf8065bc28cfe5d74e58692f
• https://github.com/bluewave-labs/Checkmate/commit/d5ec2936ad77ab773529057b442a6eb55dd578eb
• https://github.com/bluewave-labs/Checkmate/releases/tag/v3.9.2
• https://github.com/bluewave-labs/Checkmate/security/advisories/GHSA-4c6j-p2cv-wf56
• https://github.com/bluewave-labs/Checkmate/security/advisories/GHSA-4c6j-p2cv-wf56