CVE-2026-0857 Weak cryptography in Meona Client
Super administrators can read weakly hashed or plaintext passwords for legacy local accounts in Mesalvo MEONA, exposing credentials to privileged insiders.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-0857?
CVE-2026-0857 is a medium-severity vulnerability in Mesalvo Meona Client, published on 20 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Use of a Password Hash With Insufficient Computational Effort in Mesalvo MEONA (MEONA Server and MEONA Client) for user accounts whose password was last set under a version before MEONA 2024.10. MEONA versions before 2024.10 protected stored passwords with SHA-1 (versions from October 2015) or stored them without protection (earlier versions). Since MEONA 2024.10 (June 2024) Argon2 is the default method and every password that is set or changed is stored with Argon2; passwords last set under an earlier version keep the earlier method until they are changed. An administrator could in addition select the storage method per account. A MEONA super administrator can read the stored value of such accounts in the user administration of the MEONA Client or export it through administrative database functions. Only accounts managed locally in MEONA are affected; accounts authenticated through the operating hospital's directory service (Active Directory / Entra ID) have no password stored in MEONA. In typical installations end users authenticate through the directory service and local accounts are limited to emergency and technical accounts. Exploitation requires super administrator permissions in MEONA (or direct access to the MEONA database) from within the operating hospital's network; MEONA is operated exclusively within closed hospital networks without exposure to the public Internet, and 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. Installations in which every password has been set or changed under MEONA 2024.10 or later are not affected. Mesalvo is not aware of any exploitation outside the reported security test. This issue affects MEONA Server and MEONA Client in versions 2024.10, 2025.04 and 2026.03 (for accounts with passwords last set under earlier versions). MEONA 2025.04.24 and 2026.03.02 (planned Q4 2026) remove the legacy storage methods, require every affected account to set a new Argon2-protected password at next logon, and no longer display stored credential values in the user administration. See Mesalvo Security Advisory MSA-2026-002.
Weakness: CWE-916
Which versions are affected by CVE-2026-0857?
How do I fix CVE-2026-0857?
No fix has been published for CVE-2026-0857 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-0857 being exploited?
There is no known exploitation of CVE-2026-0857 in the wild and no public exploit code.
Sources
Also known as GHSA-49qv-652v-577v.