CVE-2026-70656 — Checkmate: Regular Expression Denial of Service (ReDoS) via User-Controlled Regex in Monitor Advanced Matching

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
bluewave-labs / Checkmate	affected >= 3.5.1, < 3.9.2

CWE

CWE-1333

References

ADP enrichment

CISA-ADP

No English description supplied.

https://github.com/bluewave-labs/Checkmate/security/advisories/GHSA-4c6j-p2cv-wf56