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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 7 Jan 2025. Known ransomware use
HarmonyApplication · Cleo

CVE-2024-55956

CRITICAL · 9.8 CVSS v3.1 Published 2024-12-13
Fix available
A fix is available. Upgrade to 5.8.0.24 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild Ransomware High EPSS Public exploit Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In Cleo Harmony before 5.8.0.24, VLTrader before 5.8.0.24, and LexiCom before 5.8.0.24, an unauthenticated user can import and execute arbitrary Bash or PowerShell commands on the host system by leveraging the default settings of the Autorun directory.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

This is a critical command injection vulnerability in Cleo integration products (Harmony, VLTrader, LexiCom) where an unauthenticated attacker can execute arbitrary Bash or PowerShell commands by importing malicious files through the Autorun directory, which retains default permissive settings.

MitigationImmediately upgrade to version 5.8.0.24 or later for all affected products. If immediate patching is not possible, disable or strictly control the Autorun directory functionality and implement network segmentation to limit exposure to unauthenticated users.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
HarmonyApplication
Affected:< 5.8.0.24
LexicomApplication
Affected:< 5.8.0.24
VltraderApplication
Affected:< 5.8.0.24

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Cleo products
    Locate Cleo Harmony, VLTrader, or LexiCom installations on the system by checking common installation directories or running product-specific processes
    Affected if Any of these three Cleo products are present on the system
  2. Determine installed product version
    Use the product's built-in about or version information function, or check version metadata files in the installation directory
    Affected if The installed version is lower than 5.8.0.24
  3. Verify Autorun directory configuration
    Examine the product configuration files or settings to identify the configured Autorun directory path and confirm it is enabled
    Affected if Autorun directory is configured and enabled using default settings
  4. Check network exposure
    Review firewall rules or network configuration to determine if the product's management or import interfaces are accessible from untrusted networks
    Affected if The product is accessible from untrusted or external networks without authentication restrictions

The environment is affected if any Cleo Harmony, VLTrader, or LexiCom version below 5.8.0.24 is installed with the Autorun feature enabled and accessible.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.8.0.24 or later
Fixed in 5.8.0.24
Interim mitigation

Immediately upgrade to version 5.8.0.24 or later for all affected products. If immediate patching is not possible, disable or strictly control the Autorun directory functionality and implement network segmentation to limit exposure to unauthenticated users.

Recommended fix High confidence

Cleo Harmony 5.8.0.24 | Cleo VLTrader 5.8.0.24 | Cleo LexiCom 5.8.0.24

  1. 1. Obtain the fixed version (5.8.0.24) from the official Cleo support portal at support.cleo.com
  2. 2. Create a complete backup of the current Cleo Harmony, VLTrader, or LexiCom installation, including all configuration files and data directories
  3. 3. Stop the Cleo application service to ensure no active processes during the upgrade
  4. 4. Install or apply version 5.8.0.24 of the affected product (Harmony, VLTrader, or LexiCom) following standard upgrade procedures
  5. 5. Restart the Cleo application service after installation completes
  6. 6. Verify the installation was successful by checking the application version and ensuring basic functionality works
  7. 7. Review the Autorun directory configuration to confirm it aligns with secure practices
Caveat Standard minor version upgrade - test in non-production environment first to confirm compatibility with existing workflows

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Harmony Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2024-55956 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data