CVE-2026-0856

Estado: AplazadaAlta (7.8)—

Improper Access Control vulnerability in Mesalvo MEONA (MEONA Client and MEONA Server) allows an authenticated MEONA user to access administrative functions of the MEONA Client (admin panel). The MEONA Server does not independently verify the role asserted by the MEONA Client. A user who holds a valid MEONA user account and is able to execute a modified copy of the MEONA Client on a device within the operating hospital's network can assert an administrator role and access administrative functions with regular user credentials.

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Exploitation requires: (1) a valid MEONA user account issued by the operating hospital; (2) network access to the MEONA Server, which is operated exclusively within closed hospital networks without exposure to the public Internet (where a hospital permits remote access to that network at all, it is only through the hospital's own remote-access infrastructure (e.g. VPN) under the hospital's control); (3) the ability to modify MEONA Client binaries and to execute the modified copy on a device in that network. On managed devices with application control, as recommended in Mesalvo's hardening guidance (MSA-2026-001), this requires local administrator privileges on the device. Mesalvo is not aware of any exploitation outside the reported security test. This issue affects MEONA Client and MEONA Server in versions 2024.10, 2025.04 and 2026.03. Mitigations are available with MEONA 2025.04.24 and 2026.03.02 (planned Q4 2026); see Mesalvo Security Advisory MSA-2026-001.

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 7.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.13%
Percentil entre todas las CVEs puntuadas: 2
Fecha de la puntuación: 6/10/2026

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation95 %
Impacto principalT1548 Abuse Elevation Control Mechanismprivilege escalation85 %
Impacto secundarioT1078.001 Default Accountsstealth · persistence · privilege escalation · initial access80 %

Acceso local (AV:L) sin interacción permite escalada: usuario autenticado modifica cliente para asumir rol admin sin verificación del servidor, obteniendo privilegios elevados y funciones administrativas con credenciales regulares.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Execution Prevention Update Software User Account Management Threat Intelligence Program Restrict File and Directory Permissions Privileged Account Management

Tecnologías afectadas (2)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Mesalvo — Meona Client Launcher Component^AI Mesalvo — Meona Server Component^AI

CWE

CWE-284

Referencias

https://mesalvo.com/en/vdp/advisories/msa-2026-001.pdf

JSON original (NVD)

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{
  "id": "CVE-2026-0856",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-0856",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-05-20T12:27:02.745163Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "a6d3dc9e-0591-4a13-bce7-0f5b31ff6158",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 1.8
      }
    ]
  },
  "affected": [
    {
      "source": "a6d3dc9e-0591-4a13-bce7-0f5b31ff6158",
      "affectedData": [
        {
          "vendor": "Mesalvo",
          "product": "Meona Client",
          "versions": [
            {
              "status": "affected",
              "version": "2024.10",
              "versionType": "custom"
            },
            {
              "status": "affected",
              "version": "2025.04",
              "versionType": "custom"
            },
            {
              "status": "affected",
              "version": "2026.03",
              "versionType": "custom"
            }
          ],
          "defaultStatus": "unaffected"
        },
        {
          "vendor": "Mesalvo",
          "product": "Meona Server",
          "versions": [
            {
              "status": "affected",
              "version": "2024.10",
              "versionType": "custom"
            },
            {
              "status": "affected",
              "version": "2025.04",
              "versionType": "custom"
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            {
              "status": "affected",
              "version": "2026.03",
              "versionType": "custom"
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          "defaultStatus": "unaffected"
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  ],
  "published": "2026-05-20T11:16:25.780",
  "references": [
    {
      "url": "https://mesalvo.com/en/vdp/advisories/msa-2026-001.pdf",
      "source": "a6d3dc9e-0591-4a13-bce7-0f5b31ff6158"
    }
  ],
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "a6d3dc9e-0591-4a13-bce7-0f5b31ff6158",
      "description": [
        {
          "lang": "en",
          "value": "CWE-284"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Improper Access Control vulnerability in Mesalvo MEONA (MEONA Client and MEONA Server) allows an authenticated MEONA user to access administrative functions of the MEONA Client (admin panel). The MEONA Server does not independently verify the role asserted by the MEONA Client. A user who holds a valid MEONA user account and is able to execute a modified copy of the MEONA Client on a device within the operating hospital's network can assert an administrator role and access administrative functions with regular user credentials.\nExploitation requires: (1) a valid MEONA user account issued by the operating hospital; (2) network access to the MEONA Server, which is operated exclusively within closed hospital networks without exposure to the public Internet (where a hospital permits remote access to that network at all, it is only through the hospital's own remote-access infrastructure (e.g. VPN) under the hospital's control); (3) the ability to modify MEONA Client binaries and to execute the modified copy on a device in that network. On managed devices with application control, as recommended in Mesalvo's hardening guidance (MSA-2026-001), this requires local administrator privileges on the device. Mesalvo is not aware of any exploitation outside the reported security test.\nThis issue affects MEONA Client and MEONA Server in versions 2024.10, 2025.04 and 2026.03. Mitigations are available with MEONA 2025.04.24 and 2026.03.02 (planned Q4 2026); see Mesalvo Security Advisory MSA-2026-001."
    },
    {
      "lang": "es",
      "value": "Vulnerabilidad de control de acceso inadecuado en el Componente Lanzador de Cliente Mesalvo Meona, Componente de Servidor Mesalvo Meona permite a un usuario normal obtener acceso al panel de administración. Este problema afecta al Componente Lanzador de Cliente Meona: hasta 19.06.2020 15:11:49; Componente de Servidor Meona: hasta 2025.04 5+323020."
    }
  ],
  "lastModified": "2026-09-25T16:17:24.047",
  "sourceIdentifier": "a6d3dc9e-0591-4a13-bce7-0f5b31ff6158"
}