CVE-2026-0857

Executive Summary

CVE-2026-0857 is a high-impact local information disclosure vulnerability affecting the Mesalvo Meona Clinical Information System, specifically the Client Launcher Component (through 19.06.2020 15:11:49) and the Server Component (through 2025.04 5+323020). The flaw stems from Cleartext Storage of Sensitive Information in Memory (CWE-316), allowing an attacker with local system access and high privileges to extract sensitive data from process memory. With a CVSS score of 6.0 (Medium severity) but a High confidentiality impact rating, this vulnerability poses a significant risk to healthcare organizations running Meona, as it can expose patient data, credentials, or authentication tokens stored in cleartext memory. No patch is currently available, and the CVE has a very low EPSS score (0.00101), indicating limited active exploitation in the wild.

Technical Analysis

The vulnerability resides in how the Mesalvo Meona Client Launcher and Server Components handle sensitive information in memory. CWE-316 (Cleartext Storage of Sensitive Information in Memory) indicates that the application stores critical data—such as passwords, session tokens, encryption keys, or patient health information (PHI)—in plaintext within process memory without using secure memory management techniques like Windows DPAPI, CryptProtectMemory, or equivalent OS-level memory encryption mechanisms.

Affected Components:

• Client Launcher Component: Versions through 19.06.2020 15:11:49
• Server Component: Versions through 2025.04 5+323020

Attack Vector and Access Requirements: The CVSS vector AV:L/AC:L/PR:H/UI:R/S:U/C:H/I:N/A:N defines the exploitation characteristics:

• Attack Vector (AV:L): Local — the attacker must have local access to either a Meona client workstation or the Meona server machine
• Attack Complexity (AC:L): Low — no special conditions or race conditions are required
• Privileges Required (PR:H): High — the attacker needs administrative privileges on the target system
• User Interaction (UI:R): Required — the attacker needs a user to perform a specific action, potentially to trigger the vulnerable code path or to access the memory of an active session
• Confidentiality Impact (C:H): High — substantial data exposure is possible

Vulnerable Code Paths: The Client Launcher Component likely handles authentication credentials for connecting to the Meona server. During the launch process, it may store the user's password or a shared secret in a mutable character array (String object in Java or char[] in C/C++) without zeroing the memory afterward. Java String objects are immutable and cannot be wiped from memory, making them a prime suspect for this CWE class. If the launcher uses String password = ... instead of char[] password, the credentials remain in the JVM heap until garbage collection, and even then, the underlying char array is not zeroed.

The Server Component likely maintains an authentication session store or a token cache in memory. If it handles incoming client authentication requests, it may hold passwords, hashes, or session keys in cleartext within heap allocations that can be dumped using tools like procdump (for Windows) or gcore (for Linux).

Attack Surface:

• Workstations: Healthcare staff running the Meona client launcher on Windows workstations
• Servers: The Meona server infrastructure hosting patient data and authentication services

Potential for Memory Dump: High-privilege local attackers can create a process dump of the Meona client or server process using native OS tools (Task Manager on Windows, gcore on Linux) or third-party tools (procdump, gdb). They can then parse the dump for cleartext strings, credentials, or tokens using tools like strings (Linux) or specialized tools like Mimikatz (for Windows credentials) or Volatility (memory forensics framework).

Exploitation Scenarios

Scenario 1: Healthcare Insider Threat on a Meona Client Workstation

1. Reconnaissance and Target Identification: A privileged insider (e.g., a disgruntled IT administrator) identifies a nurse's workstation running the Meona Client Launcher. The attacker has administrative rights on the workstation through domain admin credentials or local admin access.

2. Weaponization and Trigger: The attacker waits until the nurse logs into Meona (triggering user interaction UI:R). Once the client is running, the attacker opens Task Manager (or PowerShell equivalent) and initiates a full memory dump of the MeonaClient.exe process:

   procdump64.exe -ma MeonaClient.exe meona_dump.dmp
   

   Alternatively, on Linux (if used), the attacker could run:

   sudo gcore -o meona_dump <PID>
   

3. Payload and Execution: The attacker analyzes the memory dump. Since the vulnerability involves cleartext storage, the credentials are recoverable. The attacker runs:

   strings meona_dump.dmp | grep -i -E "user|pass|token|auth"
   

   Given the cleartext storage nature, the attacker likely finds the active session token or the password used for the Meona server connection. Because the Client Launcher may also have logged the username and password used during the SSO handshake, the attacker extracts domain credentials or Meona-specific credentials.

4. Post-Exploitation: The attacker uses the extracted credentials to access the Meona server directly, bypassing client-side security controls. This allows the attacker to view patient records, prescribe medications, alter treatment plans, or exfiltrate PHI, potentially violating HIPAA or GDPR depending on the jurisdiction.

Scenario 2: Server-Side Token Theft from a Meona Server

1. Reconnaissance and Target Identification: The attacker, with local administrative access to the Meona server (acquired through a previous vulnerability or insider access), identifies the MeonaServer process running and holding active session tokens for connected clients.

2. Weaponization and Trigger: The attacker triggers a memory dump of the server process. Since the server component stores session tokens in cleartext memory (per CWE-316), a simple Windows Memory Dump using rundll32.exe C:\Windows\System32\comsvcs.dll, MiniDump <PID> C:\temp\meona_server.dmp full captures the sensitive data.

3. Payload and Execution: The attacker parses the dump for authentication tokens using a memory forensics framework:

   volatility -f meona_server.dmp --profile=Win10x64_19041 hashdump
   volatility -f meona_server.dmp --profile=Win10x64_19041 secretsdump
   

   Beyond OS-level hashes, the attacker searches the heap memory for Meona-specific session identifiers or JWTs by searching for the token string patterns defined in the application's session management code. Because Meona stores these in cleartext, they are directly extractable without decryption.

4. Post-Exploitation: The attacker replays the extracted session tokens against the Meona server API to impersonate legitimate users. This allows the attacker to access patient data across multiple accounts without re-authentication, potentially enabling mass PHI exfiltration or unauthorized data modification.

Impact Assessment

Confidentiality Impact (High): The primary impact is confidentiality. CWE-316 directly leads to the exposure of sensitive information. In a clinical context, this includes:

• Patient health records (diagnoses, medications, lab results)
• Authentication credentials (domain passwords, Meona tokens)
• Possibly payment or insurance information depending on the deployment configuration

Integrity and Availability Impact (None): The CVSS vector shows no direct impact on integrity (I:N) or availability (A:N). However, compromised credentials can be leveraged for lateral movement, which could lead to data modification or ransomware deployment in downstream attacks.

Affected Systems and Blast Radius:

• Client Workstations: All workstations running the Meona Client Launcher component (version through 19.06.2020)
• Server Infrastructure: Meona Server Component (through 2025.04 5+323020)
• The blast radius is contained to systems with the Meona software installed. However, because Meona is a clinical information system, the data impact is disproportionately high compared to a generic enterprise application. A single compromised deployment could expose data for an entire medical practice or hospital department.

Business Impact:

• Regulatory fines for HIPAA (Health Insurance Portability and Accountability Act) or GDPR non-compliance
• Reputational damage to the healthcare organization
• Legal action from affected patients
• Operational disruption during incident investigation and remediation

CVSS Subscore Analysis:

• The High confidentiality subscore drives the overall Medium severity rating. Even though the attack requires elevated privileges and local access, the high data-exposure potential justifies a Medium-High operational risk for healthcare environments.

Detection Guidance

Detection for this vulnerability focuses on identifying abnormal memory dump activities, privileged process memory access, and suspicious credentials-theft behavior on Meona systems.

Sigma Rule

title: Suspicious Memory Dump of Meona Client or Server Process
id: 1a2b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects the creation of a memory dump for the Meona Client Launcher or Meona Server process, indicative of an attempt to exploit CVE-2026-0857 (cleartext sensitive data in memory).
author: Valtersit Threat Intelligence
date: 2025/05/14
logsource:
    category: process_creation
    product: windows
detection:
    selection_dump_tools:
        Image|endswith:
            - '\procdump.exe'
            - '\procdump64.exe'
            - '\rundll32.exe'
            - '\powershell.exe'
            - '\cmd.exe'
        CommandLine|contains:
            - 'Meona'
            - 'meona'
            - 'MiniDump'
            - '-ma'
            - '-accepteula'
    selection_target_process:
        CommandLine|contains:
            - 'MeonaClient'
            - 'MeonaServer'
            - 'meona_'
    condition: selection_dump_tools and selection_target_process
    timeframe: 30m
level: high
falsepositives:
    - Legitimate troubleshooting by IT administrators performing memory dumps for support purposes
fields:
    - Image
    - CommandLine
    - User
tags:
    - attack.t1003.001
    - attack.collection
    - cve.2026-0857

YARA Rule

rule CVE_2026_0857_Meona_Cleartext_Memory {
    meta:
        author = "Valtersit Threat Intelligence"
        description = "Detects Meona-related cleartext credential patterns in memory dumps and binary artifacts"
        date = "2025-05-14"
        cve = "CVE-2026-0857"
        cwe = "CWE-316"
        severity = "medium"
    strings:
        $meona_ident = "Meona" ascii wide nocase
        $client_launcher = "ClientLauncher" ascii wide nocase ascii
        $server_component = "ServerComponent" ascii wide nocase ascii
        $auth_token = /(session_token|auth_token|access_token|refresh_token)=[A-Za-z0-9\-_\.]{20,}/ nocase ascii
        $password_pattern = /(password|passwd|pwd)=[^\s&]{6,}/ nocase ascii
        $user_pattern = /(username|user|userid)=[A-Za-z0-9_\-\.]{4,}/ nocase ascii
        $connection_string = /meona:\/\/[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}:\d+/ ascii nocase
    condition:
        uint16(0) == 0x5A4D and
        (($meona_ident and $client_launcher) or ($meona_ident and $server_component)) and
        any of ($auth_token, $password_pattern, $user_pattern, $connection_string)
}

Suricata IDS Rule

alert tcp any any -> any any (msg:"CVE-2026-0857 - Potential Meona Credential Exfiltration via SMB Memory Dump"; flow:to_server,established; content:"|54 00 68 00 65 00 20 00 4d 00 65 00 6f 00 6e 00 61 00|"; nocase; content:"|63 00 6f 00 6e 00 6e 00 65 00 63 00 74 00 69 00 6f 00 6e 00|"; nocase; distance:0; content:"|72 00 65 00 6d 00 6f 00 74 00 65 00 20 00 64 00 69 00 73 00 6b 00 20 00 74 00 65 00 61 00 6d 00|"; nocase; distance:0; cla ssification:attempted-user; priority:1; sid:20260857; rev:1;)

Note: This rule uses the Unicode (UTF-16LE) hex representation for the strings "The Meona connection remote disk team" which are likely present in SMB file-sharing traffic when a memory dump file is transferred over the network. Ensure proper rule syntax adjustment in production.

Elastic Detection

// EQL query to detect memory dump creation targeting Meona processes
sequence by host.id, user.name with maxspan=10m
  [process where event.type == "start" and 
   (process.name : "procdump*.exe" or process.name : "rundll32.exe" or process.name : "powershell.exe") and
   (process.command_line : "*Meona*" or process.command_line : "*MiniDump*")]
  [file where event.type == "creation" and
   (file.name : "*.dmp" or file.name : "*.dump") and
   file.path : "*temp*"]

Detection rationale: This rule looks for the combination of a memory dump tool being invoked with Meona-related arguments, followed by the creation of a .dmp file in a temporary directory. This sequence represents the core attack pattern for CVE-2026-0857 exploitation.

Splunk SPL Query

index=windows source="WinEventLog:Security" OR index=endpoint
| where match(eventcode, "4688") OR sourcetype="WinEventLog:Security"
| rex field=CommandLine "(?i)(?<tool>procdump|rundll32|powershell|cmd)"
| rex field=CommandLine "(?i)(?<target>Meona|meona)"
| search tool=* target=*
| stats count by user, host, CommandLine, _time
| eval suspicious = if(match(CommandLine, "(?i)(-ma|MiniDump|meona)"), "TRUE", "FALSE")
| where suspicious = "TRUE"
| table _time, host, user, CommandLine, count
| sort - _time

Alternative SPL for process-level events:

index=windows EventCode=4688
| spath input=New_Process_Name output=process_name
| spath input=CommandLine output=cmdline
| where match(cmdline, "(?i)(Meona|meona)") AND match(cmdline, "(?i)(procdump|rundll32|MiniDump|-ma)")
| eval threat = "CVE-2026-0857_Exploitation_Attempt"
| table _time, host, user, process_name, cmdline

Wazuh OSSEC Rule

<group name="meona,cve-2026-0857,">
    <rule id="302801" level="12">
        <decoded_as>syscheck</decoded_as>
        <field name="file">.*(\.dmp|\.dump)$</field>
        <description>CVE-2026-0857: Potential memory dump file created - possible exploitation attempt on Meona system</description>
        <group>meona_cve_2026_0857,</group>
        <mitre>
            <id>T1003.001</id>
        </mitre>
        <options>no_full_log</options>
    </rule>

    <rule id="302802" level="14" frequency="5" timeframe="60">
        <if_matched_sid>302801</if_matched_sid>
        <description>CVE-2026-0857: Multiple memory dump file creations detected - active exploitation likely</description>
        <group>meona_cve_2026_0857,</group>
        <mitre>
            <id>T1003.001</id>
        </mitre>
    </rule>

    <rule id="302803" level="10">
        <decoded_as>windows-security</decoded_as>
        <field name="event_id">^4688$</field>
        <match>procdump|rundll32|MiniDump</match>
        <regex>command_line -> .*[Mm]eona.*</regex>
        <description>CVE-2026-0857: Suspicious process creation targeting Meona components for memory dumps</description>
        <group>meona_cve_2026_0857,</group>
        <mitre>
            <id>T1003.001</id>
        </mitre>
    </rule>
</group>

Mitigation & Patch Guidance

Patch Confidence: 0/4 — UNPATCHED — No patch evidence from any tracked source.

No vendor advisory or patch is currently available for CVE-2026-0857. The patch confidence score of 0/4, combined with the absence of affected version data from OSV, indicates that Mesalvo has not publicly acknowledged or remediated this vulnerability.

1) Immediate Mitigations

• Restrict Local Administrative Access: Since the vulnerability requires High privileges (PR:H), limiting local admin rights on all Meona client workstations and server infrastructure severely reduces the attack surface. Implement the principle of least privilege (PoLP) using Group Policy (Windows) or RBAC (Linux).
• Deploy Application Whitelisting: Use AppLocker (Windows) or equivalent on Linux to prevent execution of memory dump tools (procdump, rundll32 with MiniDump) by unauthorized users.
• Monitor Privileged User Activity: Enable comprehensive auditing of all privileged user sessions on Meona systems. Pay special attention to usage of Task Manager, procdump, rundll32, and similar tools.
• Secure Workstation Physical Access: Because AV:L requires physical or console access, ensure physical security of Meona workstations. Disable USB ports and restrict console access in clinical areas.
• Implement Memory Encryption: Where technically feasible, consider using Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR) to complicate memory exploitation. These do not fix CWE-316 but add a security layer.

2) Patch/Upgrade Steps

• Contact Mesalvo Support: Reach out to Mesalvo directly for any private hotfixes or beta builds that may address this vulnerability. Since the issue affects both the Client Launcher (through 19.06.2020) and Server (through 2025.04 5+323020), ensure you are subscribed to vendor updates.
• Monitor Vendor Advisory Channels: Although no patch exists today (patch confidence 0/4), the vendor may release an update. Review the NVD entry and monitor Mesalvo's official communication channels for a patched version.
• Refer to NVD for Update Notifications: The NVD page for CVE-2026-0857 may be updated with patch references once the vendor responds. Check this resource regularly: NVD CVE-2026-0857.

3) Long-Term Hardening

• Memory Security Review: Conduct a code review of the Meona Client Launcher and Server Components (if you have access to source code or vendor support) focusing on CWE-316. Ensure credentials are stored as char[] or SecureString (not String) and are zeroed after use.
• Work with Vendor: Coordinate with Mesalvo development teams to implement secure memory management practices, including the use of OS-level memory protection APIs (CryptProtectMemory / CryptUnprotectMemory on Windows, or keyrings on Linux).
• Data-at-Rest Encryption: While the vulnerability is memory-focused, ensure that sensitive data stored on disk (logs, configuration files, cache) is encrypted with strong algorithms.
• Segmentation: Separate Meona server infrastructure into a dedicated security zone or VLAN, with strict firewall rules preventing lateral movement from compromised workstations.
• Conduct Regular Red Team Assessments: Perform periodic penetration tests that specifically test for local privilege escalation and memory disclosure scenarios on Meona deployments.

References

1. NVD Entry for CVE-2026-0857 — https://nvd.nist.gov/vuln/detail/CVE-2026-0857

   • Official vulnerability entry with CVSS scoring, CWE classification (CWE-316), and affected version information.

2. CWE-316: Cleartext Storage of Sensitive Information in Memory — https://cwe.mitre.org/data/definitions/316.html

   • Comprehensive technical description of the vulnerability class and common remediation patterns.

3. Mesalvo Meona Product Information — https://www.mesalvo.com/en/meona

   • Vendor product page for the affected clinical information system, providing context on deployment environments and architecture.

4. MITRE ATT&CK Technique T1003 - OS Credential Dumping — https://attack.mitre.org/techniques/T1003/

   • Framework reference for the exploitation technique likely used to leverage this vulnerability.

5. CISA Known Exploited Vulnerabilities (KEV) Catalog — https://www.cisa.gov/known-exploited-vulnerabilities-catalog

   • Confirms CISA KEV status is NO; the vulnerability has not been listed as exploited in the wild by CISA. The EPSS score of 0.00101 further confirms low active exploitation probability; no known threat actor campaigns or exploit-in-the-wild evidence is documented at this time.