Vulnerability in Bluewave-Labs Checkmate
CVE-2026-70656
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.
Vulnerability class: ReDoS (Regular Expression Denial of Service)
CVSS v3 metric
CVSS v3 base score 4.9 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Bluewave-labs Checkmate — versions >= 3.5.1, < 3.9.2
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_CONFIRM)
Frequently asked questions
- What is CVE-2026-70656?
- CVE-2026-70656 is a medium-severity vulnerability in Bluewave-Labs Checkmate, classified under Inefficient Regular Expression Complexity. CVSS score: 4.9/10. Published 2026-08-21.
- How severe is CVE-2026-70656?
- Medium severity. CVSS v3 base score is 4.9 out of 10.