CVE-2026-70656

MEDIUMPre-NVD 4.94.9—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 66% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this week
4.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.9Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
4.9
EG Score
4.9(medium)
EG Risk
27(Track)
EG Risk 27/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity49% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
34%
KEV
Not listed

Published

August 21, 2026

Last Modified

August 21, 2026

Advisory Details (5)

Auto-updated Aug 21, 2026
🔬 Proof of concept available. Patch available. Sources: github_release, github, github_commit.
github Patch Available🟡 PoC Available

Regular Expression Denial of Service (ReDoS) via User-Controlled Regex in Monitor Advanced Matching · Advisory · bluewave-labs/Checkmate · GitHub

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

Checkmate v3.9.2

Patch available: bluewave-labs/Checkmate v3.9.2

https://github.com/bluewave-labs/Checkmate/releases/tag/v3.9.2
github_commit

commit d5ec2936ad77 (bluewave-labs/Checkmate)

Fix landed in bluewave-labs/Checkmate commit d5ec2936ad77 — awaiting tagged release

https://github.com/bluewave-labs/Checkmate/commit/d5ec2936ad77ab773529057b442a6eb55dd578eb
github_commit

commit adba25269c45 (bluewave-labs/Checkmate)

Fix landed in bluewave-labs/Checkmate commit adba25269c45 — awaiting tagged release

https://github.com/bluewave-labs/Checkmate/commit/adba25269c455878bf8065bc28cfe5d74e58692f
github_commit

commit 0df71d6356c8 (bluewave-labs/Checkmate)

Fix landed in bluewave-labs/Checkmate commit 0df71d6356c8 — awaiting tagged release

https://github.com/bluewave-labs/Checkmate/commit/0df71d6356c87c747e0b796b0c34e33f2a5203fa

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 8× in last 7d / 8× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-26 00:37 UTCEG score recompute
  2. 2026-08-25 13:49 UTCEPSS rescore
  3. 2026-08-24 23:19 UTCEG score recompute
  4. 2026-08-23 22:00 UTCEG score recompute
  5. 2026-08-23 00:19 UTCEPSS rescore
  6. 2026-08-21 18:18 UTCEG score recompute
  7. 2026-08-21 18:04 UTCEG score recompute
  8. 2026-08-21 18:04 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-70656?
CVE-2026-70656 is a medium vulnerability published on August 21, 2026. 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…
When was CVE-2026-70656 disclosed?
CVE-2026-70656 was first published in the National Vulnerability Database on August 21, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-70656 actively exploited?
CVE-2026-70656 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 65.6% of all scored CVEs.
What is the CVSS score of CVE-2026-70656?
CVE-2026-70656 has a CVSS v3 base score of 4.9 (NVD).
How do I remediate CVE-2026-70656?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-70656, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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