{"id":"CVE-2026-70656","title":"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","summary":"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 c…","severity":"medium","cvss":4.9,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-1333"],"published":"2026-08-21","updated":"2026-09-18","sourceUpdated":"2026-09-18T20:09:01.757","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-70656","references":[{"url":"https://github.com/bluewave-labs/Checkmate/commit/0df71d6356c87c747e0b796b0c34e33f2a5203fa","label":"security-advisories@github.com"},{"url":"https://github.com/bluewave-labs/Checkmate/commit/adba25269c455878bf8065bc28cfe5d74e58692f","label":"security-advisories@github.com"},{"url":"https://github.com/bluewave-labs/Checkmate/commit/d5ec2936ad77ab773529057b442a6eb55dd578eb","label":"security-advisories@github.com"},{"url":"https://github.com/bluewave-labs/Checkmate/releases/tag/v3.9.2","label":"security-advisories@github.com"},{"url":"https://github.com/bluewave-labs/Checkmate/security/advisories/GHSA-4c6j-p2cv-wf56","label":"security-advisories@github.com"},{"url":"https://github.com/bluewave-labs/Checkmate/security/advisories/GHSA-4c6j-p2cv-wf56","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"tags":["nvd"],"epss":0.00505,"epssPercentile":0.4203,"ingestedAt":"2026-09-18T20:51:25.655Z","slug":"CVE-2026-70656","body":"## Overview\n\nCheckmate 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":27,"depthScoreParts":{"impact":27,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}