CVE-2026-70656
Checkmate: Regular Expression Denial of Service (ReDoS) via User-Controlled Regex in Monitor Advanced Matching
- 4.9MediumCVSS base score
- 0.59%Exploitation in 30 daysEPSS · top 51% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- YesPublic exploitsa reference or SSVC says so
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.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. A reference of the record is tagged as an exploit. CISA's SSVC rates its exploitation: a proof of concept is public.
Show the exploits1
References tagged exploit1 reference
- https://github.com/bluewave-labs/Checkmate/security/advisories/GHSA-4c6j-p2cv-wf56 (opens in a new tab)x_refsource_CONFIRMexploit
Timeline
ID reserved
By GitHub_M
- 17 days later
· 17 days later
Published
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | Medium4.9 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Deferred | 3.1 | Medium4.9 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.59% · top 51% of all CVEs (11 Nov 2026)
- CISA SSVC
- Exploitation: poc · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 4.9.
Affected products
- affected >= 3.5.1, < 3.9.2
References
References5
- https://github.com/bluewave-labs/Checkmate/security/advisories/GHSA-4c6j-p2cv-wf56 (opens in a new tab)x_refsource_CONFIRMexploit
- https://github.com/bluewave-labs/Checkmate/commit/0df71d6356c87c747e0b796b0c34e33f2a5203fa (opens in a new tab)x_refsource_MISC
- https://github.com/bluewave-labs/Checkmate/commit/adba25269c455878bf8065bc28cfe5d74e58692f (opens in a new tab)x_refsource_MISC
- https://github.com/bluewave-labs/Checkmate/commit/d5ec2936ad77ab773529057b442a6eb55dd578eb (opens in a new tab)x_refsource_MISC
- https://github.com/bluewave-labs/Checkmate/releases/tag/v3.9.2 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-64038 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-70656)Record last updated .