Security Resilience

CVE-2026-66420

Public PoC
Published
30 July 2026
Modified
09 September 2026
CVSS Score v4 8.6
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0022 12th percentile
Risk Priority 55 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-66420 is a high-severity Origin Validation Error (CWE-346) vulnerability. Its CVSS base score is 8.6 (High).

Operationally, ranked at the 12th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to AC-4 (Information Flow Enforcement) and IA-3 (Device Identification and Authentication) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A07:2025 Authentication Failures

EU & UK References

Vulnerability Data

MeshCentral 1.1.21 contains a cross-site WebSocket hijacking protection bypass vulnerability that allows unauthenticated remote attackers to hijack authenticated administrator sessions by exploiting an unconditional early return in the CheckWebServerOriginName() function within webserver.js when self-signed certificates are in use. Attackers can…

more

open cross-origin WebSocket connections to any of the twelve WebSocket endpoints, send crafted action commands to exfiltrate the server sessionKey used to sign session cookies, forge session tokens as arbitrary users, and gain full remote control of all managed devices governed by the MeshCentral instance.

CWE(s)
CWE-346

Related Threats

CVEs Like This One

CVE-2024-13068Shared CWE-346
CVE-2026-17981Shared CWE-346
CVE-2026-25604Shared CWE-346
CVE-2026-17720Shared CWE-346
CVE-2026-21790Shared CWE-346
CVE-2025-53600Shared CWE-346
CVE-2026-11181Shared CWE-346
CVE-2026-17783Shared CWE-346
CVE-2026-85152Shared CWE-346
CVE-2025-13947Shared CWE-346

Affected Assets

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

AC-4 Information Flow Enforcement good match

Information flow enforcement directly requires validating the source of data before allowing transmission or receipt.

IA-3 Device Identification and Authentication good match

Device identification and authentication mandates verifying the source before establishing connections.

SC-23 Session Authenticity good match

Session authenticity mechanisms require validation that communications originate from the expected party.

SC-7 Boundary Protection partial match

Boundary protection at interfaces enforces checks on the origin of incoming communications.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.28 Secure coding partial match
prevents

Secure coding practices include implementing proper origin validation to prevent spoofing.

Hardening callouts derived

DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.

  • No fine-grained STIG row for CWE-346, a class-level weakness, and none of its children carries one either.

References