Vulnerability report

Exploitation attempts observed in the wild Confirmed confidence In CISA KEV

CVE-2024-55956

["Harmony"

Cleo / ["Harmony"

Watch CVE-2024-55956 Browse KEV feed
Severity
CVSS 9.8 · Critical
Confidence
Confirmed
Exploit status
Exploitation attempts observed in the wild
EPSS
94.0%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2024-55956 is an unauthenticated vulnerability affecting Cleo ["Harmony" and 2 other products. 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...

Have exploitation attempts been observed?

Yes. Exploitation attempts have been reported for this vulnerability. Previdian lists it as a known exploited vulnerability. Listed in CISA KEV. Also reported by third-party sources. Confidence is confirmed.

Who is affected?

Cleo / ["Harmony".

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

["Harmony"

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.

Published
13 Dec 2024
Exploitation Attempts Reported
17 Dec 2024
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

ransomware nuclei_scanner metasploit nessus_scanner malware cisa metasploit_scanner

CVE References

Exploitation evidence

Evidence of exploitation attempts

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploitation attempts observed in the wild

CISA

Recorded 17 Dec 2024

A trusted third party reported exploitation attempts.

Targeted by malware-related exploitation attempts

CISA

Recorded 17 Dec 2024

Exploitation attempts against this vulnerability are associated with malware-related payloads.

Proof of concept available

Nuclei Templates

Recorded 28 Apr 2025

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
CISA First 2024-12-17 00:00 UTC
CVE 2026-08-05 04:30 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
0
0
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner Reference Detected
Metasploit https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/multi/http/cleo_rce_cve_2024_55956.rb 28 Apr 2025
Nuclei https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2024/CVE-2024-55956.yaml 25 Apr 2025

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

9.8 Critical

Potential damage if exploited. Separate from whether attackers are using it.

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

EPSS

94.0%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Improper Neutralization of Special Elements used in a Command ('Command Injection') CWE-77

Recent mention · Huntress Blog

Rogue RMM Abuse: How Attackers Exploit Remote Access Tools

The Huntress SOC uncovered phishing attacks that trick employees into installing rogue RMM tools like ScreenConnect for persistent access. Learn how to spot it.

Read full advisory

All Mentions

Recent mention · Huntress Blog

Rogue RMM Abuse: How Attackers Exploit Remote Access Tools

Huntress Blog · 23 Sep 2026

The Huntress SOC uncovered phishing attacks that trick employees into installing rogue RMM tools like ScreenConnect for persistent access. Learn how to spot it.

Recent mention · Google Threat Intelligence

Written by: Casey Charrier, James Sadowski, Clement Lecigne, Vlad Stolyarov Executive Summary Google Threat Intelligence Group (GTIG) tracked 75...

Google Threat Intelligence · 29 Apr 2025

Written by: Casey Charrier, James Sadowski, Clement Lecigne, Vlad Stolyarov Executive Summary Google Threat Intelligence Group (GTIG) tracked 75 zero-day vulnerabilities exploited in the wild in 2024, a decrease from the number we identified in 2023 (98 vulnerabilities), but still an increase from 2022 (63 vulnerabilities). We divided the reviewed vulnerabilities into two main categories: end-user platforms and products (e.g., mobile devices, operating systems, and browsers) and enterprise-focused technologies, such as security software and appliances.  Vendors continue to drive...

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

Cleo Harmony < 5.8.0.24 - File Upload Vulnerability

nuclei · Created Unknown

cleo_rce_cve_2024_55956

metasploit · Created Unknown

Metasploit module for CVE-2024-55956

Timeline

From disclosure to observed exploitation attempts

  1. 04:30 UTC

    KEV confirmed by CVE

    Exploitation attempts reported by an external source

  2. 15:02 UTC

    Metasploit module available

    Exploit module available

  3. 15:02 UTC

    Public PoC available

    Public proof-of-concept code published

  4. 00:00 UTC

    Nuclei template available

    Scanner coverage available

  5. 00:00 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  6. 00:00 UTC

    Targeted by malware-related exploitation attempts

    Malware-related exploitation attempts or payloads reported

  7. 00:00 UTC

    CVE published

    Vulnerability disclosed publicly

  8. 00:00 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

Start 14-day Pro trial Read API docs
  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2024-55956

Sample API response 
{
  "cve_id": "CVE-2024-55956",
  "confidence": "Confirmed",
  "cvss_score": 9.8,
  "cvss_estimated": false,
  "epss_score": 0.93968,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}