CVE-2026-0856
Summary
| CVE | CVE-2026-0856 |
|---|---|
| State | PUBLISHED |
| Assigner | ENISA |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-05-20 11:16:25 UTC |
| Updated | 2026-09-25 16:17:24 UTC |
| Description | 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. 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. |
Risk And Classification
Primary CVSS: v3.1 7.8 HIGH from a6d3dc9e-0591-4a13-bce7-0f5b31ff6158
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS: 0.001260000 probability, percentile 0.019520000 (date 2026-09-27)
Problem Types: CWE-284 | CWE-284 CWE-284: Improper Access Control
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | a6d3dc9e-0591-4a13-bce7-0f5b31ff6158 | Secondary | 7.8 | HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | CNA | CVSS | 7.8 | HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
CVSS v3.1 Breakdown
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Mesalvo | Meona Client | affected 2024.10 custom | Not specified |
| CNA | Mesalvo | Meona Client | affected 2025.04 custom | Not specified |
| CNA | Mesalvo | Meona Client | affected 2026.03 custom | Not specified |
| CNA | Mesalvo | Meona Server | affected 2024.10 custom | Not specified |
| CNA | Mesalvo | Meona Server | affected 2025.04 custom | Not specified |
| CNA | Mesalvo | Meona Server | affected 2026.03 custom | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| mesalvo.com/en/vdp/advisories/msa-2026-001.pdf | a6d3dc9e-0591-4a13-bce7-0f5b31ff6158 | mesalvo.com | |
| seccore.at/blog/cves-meona | MITRE | seccore.at | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Additional Advisory Data
Workarounds
CNA: MEONA 2025.04.24 and 2026.03.02 (Q4 2026) introduce code signing of all MEONA Client executables and assemblies and integrity verification of the client assemblies at start-up. Operators should enforce application control on MEONA workstations so that only Mesalvo-signed binaries execute, withhold local administrator rights from clinical users, provision MEONA users through the hospital's central identity and access management, and keep the MEONA network zone segmented without Internet exposure. Details: Mesalvo Security Advisory MSA-2026-001.