{"id":"CVE-2026-70656","summary":"Checkmate: Regular Expression Denial of Service (ReDoS) via User-Controlled Regex in Monitor Advanced Matching","details":"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.","aliases":["GHSA-4c6j-p2cv-wf56"],"modified":"2026-08-23T03:53:39.563805314Z","published":"2026-08-21T17:59:28.639Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-1333"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/70xxx/CVE-2026-70656.json"},"references":[{"type":"WEB","url":"https://github.com/bluewave-labs/Checkmate/releases/tag/v3.9.2"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/70xxx/CVE-2026-70656.json"},{"type":"ADVISORY","url":"https://github.com/bluewave-labs/Checkmate/security/advisories/GHSA-4c6j-p2cv-wf56"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-70656"},{"type":"FIX","url":"https://github.com/bluewave-labs/Checkmate/commit/0df71d6356c87c747e0b796b0c34e33f2a5203fa"},{"type":"FIX","url":"https://github.com/bluewave-labs/Checkmate/commit/adba25269c455878bf8065bc28cfe5d74e58692f"},{"type":"FIX","url":"https://github.com/bluewave-labs/Checkmate/commit/d5ec2936ad77ab773529057b442a6eb55dd578eb"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/bluewave-labs/checkmate","events":[{"introduced":"c2170267e8d4653e04040f40f220966208f8dc21"},{"fixed":"0df71d6356c87c747e0b796b0c34e33f2a5203fa"},{"fixed":"adba25269c455878bf8065bc28cfe5d74e58692f"},{"fixed":"d5ec2936ad77ab773529057b442a6eb55dd578eb"},{"fixed":"d368ec5bd7af1cd81628c47a89d1d830cd415590"}],"database_specific":{"extracted_events":[{"introduced":"3.5.1"},{"fixed":"3.9.2"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["v3.9.1","v3.7.1","v3.6.1","v3.5.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-70656.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H"}]}