Cyber Resilience

CVE-2024-55956

RCE in Cleo Harmony ≤ 5.8.0.24

CISA KEVActive ExploitationEUVD ExploitedPublic PoCRansomware-linkedRCECommand Injection
Published
13 December 2024
Modified
05 August 2026
KEV Added
17 December 2024
Patch / advisory
View advisory
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.94 99.8th percentile
Risk Priority 97 floored blend · peak EPSS

Summary

CVE-2024-55956 is a critical-severity Command Injection (CWE-77) vulnerability in Cleo Harmony. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Command and Scripting Interpreter (T1059); ranked in the top 0.2% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

Cleo Harmony, VLTrader, and LexiCom versions prior to 5.8.0.24 contain a command injection vulnerability tracked as CVE-2024-55956 and CWE-77. The flaw allows an unauthenticated remote user to import and execute arbitrary Bash or PowerShell commands on the underlying host by abusing the products' default Autorun directory configuration. The issue carries a CVSS 3.1 score of 9.8, reflecting network-accessible attack complexity that requires no credentials or user interaction.

An attacker can send specially crafted files or commands to the affected transfer-management software and obtain arbitrary code execution with the privileges of the service account. Successful exploitation grants full control over the host system, enabling data theft, persistence, lateral movement, or ransomware deployment.

Cleo has published security advisories and remediation guidance directing customers to upgrade to version 5.8.0.24 or later. The vulnerability appears in CISA's Known Exploited Vulnerabilities catalog, confirming that federal agencies must apply the vendor patch according to the published timeline.

Huntress has reported active exploitation of the flaw in the wild. The associated EPSS score reached a peak of 0.9675 and currently stands at 0.9122, indicating sustained attacker interest after disclosure.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

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.

CWE(s)
CWE-77
KEV Date Added
17 December 2024

Related Threats

Threat-Actor AttributionAI

Cl0p
CISA KEV ransomware-use flag plus Huntress reporting tie active exploitation of this Cleo MFT zero-day to the Cl0p crew.

MITRE ATT&CK Enterprise Techniques

T1059 Command and Scripting Interpreter Execution
Adversaries may abuse command and script interpreters to execute commands, scripts, or binaries.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1059.001 PowerShell Execution
Adversaries may abuse PowerShell commands and scripts for execution.
attack.mitre.org →
T1059.003 Windows Command Shell Execution
Adversaries may abuse the Windows command shell for execution.
attack.mitre.org →
T1059.004 Unix Shell Execution
Adversaries may abuse Unix shell commands and scripts for execution.
attack.mitre.org →
T1059.008 Network Device CLI Execution
Adversaries may abuse scripting or built-in command line interpreters (CLI) on network devices to execute malicious command and payloads.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-50623Same product: Cleo Harmonyboth on KEV
CVE-2026-8037Same product class: managed file transferboth on KEV
CVE-2025-10035Same product class: managed file transferboth on KEV
CVE-2025-14031Same product class: managed file transfer
CVE-2015-2857Same product class: managed file transfer
CVE-2023-1389Shared CWE-77both on KEV
CVE-2012-1823Shared CWE-77both on KEV
CVE-2019-0541Shared CWE-77both on KEV
CVE-2005-2773Shared CWE-77both on KEV
CVE-2020-25079Shared CWE-77both on KEV

Affected Assets

cleo
harmony
≤ 5.8.0.24
cleo
lexicom
≤ 5.8.0.24
cleo
vltrader
≤ 5.8.0.24

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.2.3
  • V1.2.5
  • V1.2.8
  • V1.2.9

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation can discover command-construction flaws before deployment.

SI-10 Information Input Validation good match

Input validation directly stops construction of commands from untrusted data containing special elements.

SA-8 Security and Privacy Engineering Principles partial match

Secure engineering principles include proper neutralization and safe command construction practices.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require input validation and neutralization that prevent command injection.

DE.CM-09 partial match
prevents

Runtime monitoring of software and data can detect anomalous command execution resulting from injection.

ID.RA-01 partial match
prevents

Identifying recorded vulnerabilities enables remediation of command-injection flaws before exploitation.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.28 Secure coding mostly match
prevents

Secure coding standards require proper escaping and parameterization of commands, directly eliminating CWE-77.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development catches command-injection vulnerabilities before release.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle mandates input validation and command construction practices that directly prevent command injection.

A.8.26 Application security requirements partial match
prevents

Application security requirements explicitly call for controls against injection flaws including command injection.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles reduce the attack surface but do not prescribe the specific neutralization techniques needed.

A.8.31 Separation of development, test and production environments none match
none

Environment separation limits the blast radius of an exploited command injection but does not prevent the flaw itself.

References