---
id: CVE-2026-66420
title: >-
  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 C…
summary: >-
  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 C…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'
cwe:
  - CWE-346
vendor: Ylianst
product: MeshCentral
affected:
  - MeshCentral 1.1.21
published: '2026-07-30'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T20:26:18.573'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-66420'
references:
  - url: 'https://github.com/Ylianst/MeshCentral'
    label: disclosure@vulncheck.com
  - url: 'https://github.com/Ylianst/MeshCentral/commit/f04c9f4'
    label: disclosure@vulncheck.com
  - url: 'https://github.com/Ylianst/MeshCentral/pull/7882'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/meshcentral-cross-site-websocket-hijacking-via-origin-validation-bypass-on-self-signed-certificate-deployments
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-07-31T15:54:31.218334Z'
ingestedAt: '2026-09-11T03:52:34.457Z'
epss: 0.00221
epssPercentile: 0.11347
---

## Overview

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 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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.