id: CVE-2026-18577

info:
  name: N-able N-central < 2026.3.1.10 - Authentication Bypass
  author: patrick-threatmate
  severity: critical
  description: |
    N-able N-central versions through 2026.3.1 contain an authentication bypass that lets a remote unauthenticated attacker take over an administrator account and gain full control of the N-central server. CVE-2026-18577 is a bypass of the incomplete fix for CVE-2026-18556, so the 2026.3.1 Hotfix 1 build (2026.3.1.7) does not fully remediate it. Hotfix 2 (2026.3.1.10) supersedes Hotfix 1 and is the first fully fixed 2026.3 build.
  impact: |
    Unauthenticated attackers gain administrative access to the RMM console and can reach every managed endpoint through Take Control. Exploited in the wild and added to the CISA Known
  remediation: |
    Upgrade on-premises N-central to 2026.3.1.10 (2026.3 Hotfix 2) or to a later release line (2026.4 or newer). Applying Hotfix 1 (2026.3.1.7) alone is not sufficient. N-able hosted environments were mitigated by the vendor and need no customer action.
  reference:
    - https://www.n-able.com/blog/n-central-security-update-august-6-2026
    - https://status.n-able.com/2026/08/06/n-central-2026-3-hotfix-2-additional-mitigation-for-cve-2026-18577/
    - https://www.rapid7.com/blog/post/etr-cve-2026-18577-n-able-n-central-authentication-bypass-exploited-in-the-wild/
    - https://www.huntress.com/blog/n-able-vulnerability-exploitation
    - https://nvd.nist.gov/vuln/detail/CVE-2026-18577
    - https://nvd.nist.gov/vuln/detail/CVE-2026-18556
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 8.1
    cve-id: CVE-2026-18577
    epss-score: 0.54068
    epss-percentile: 0.98933
    cwe-id: CWE-288
    cpe: cpe:2.3:a:n-able:n-central:*:*:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: n-able
    product: n-central
    shodan-query: http.title:"N-central Login"
    fofa-query: title="N-central Login"
  tags: cve,cve2026,n-able,ncentral,auth-bypass,kev,passive,vkev

http:
  - method: GET
    path:
      - "{{BaseURL}}/login"

    matchers-condition: and
    matchers:
      - type: word
        condition: or
        words:
          - 'class="ncentral"'
          - 'ncentralVersion'

      - type: dsl
        dsl:
          - compare_versions(version, '< 2026.3.1.10')

    extractors:
      - type: regex
        name: version
        internal: true
        group: 1
        regex:
          - 'ncentralVersion:\s*"(202\d+\.\d+\.\d+\.\d+)"'

      - type: regex
        name: ncentral_version
        group: 1
        regex:
          - 'ncentralVersion:\s*"(202\d+\.\d+\.\d+\.\d+)"'
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