CVE-2021-1626
📋 TL;DR
This is a critical remote code execution vulnerability in MuleSoft runtime components that allows attackers to execute arbitrary code on affected systems. It affects both CloudHub and on-premise deployments running vulnerable Mule runtime versions. Organizations using Mule 4.1.x or 4.2.x before February 2, 2021 are at risk.
💻 Affected Systems
- MuleSoft Mule Runtime
📦 What is this software?
Mule by Salesforce
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attackers to execute arbitrary code, steal sensitive data, deploy ransomware, or pivot to other internal systems.
Likely Case
Unauthenticated remote code execution leading to data exfiltration, service disruption, or installation of backdoors.
If Mitigated
Limited impact if proper network segmentation, least privilege, and monitoring are in place to contain potential breaches.
🎯 Exploit Status
CVSS 9.8 indicates critical severity with low attack complexity and no authentication required.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Mule 4.2.2-HF4 or later, Mule 4.1.6-HF4 or later
Vendor Advisory: https://help.salesforce.com/articleView?id=000357382&type=1&mode=1
Restart Required: Yes
Instructions:
1. Identify affected Mule runtime versions. 2. Upgrade to patched versions: Mule 4.2.2-HF4+ or Mule 4.1.6-HF4+. 3. Restart Mule runtime instances. 4. Verify patch application.
🔧 Temporary Workarounds
Network Segmentation
allRestrict network access to Mule runtime instances to only trusted sources
Firewall Rules
allImplement strict firewall rules to limit inbound connections to Mule services
🧯 If You Can't Patch
- Isolate affected systems from internet and restrict internal network access
- Implement application-level firewalls and intrusion detection systems
🔍 How to Verify
Check if Vulnerable:
Check Mule runtime version via Mule Management Console or by examining deployment filesCheck Version:
Check mule-agent.log or use Mule Management Console to view runtime versionVerify Fix Applied:
Verify version is Mule 4.2.2-HF4+ or Mule 4.1.6-HF4+ and check for successful restart📡 Detection & Monitoring
Log Indicators:
- Unusual process execution
- Suspicious network connections from Mule runtime
- Unexpected file system modifications
Network Indicators:
- Unusual outbound connections from Mule servers
- Suspicious payloads to Mule runtime ports
SIEM Query:
source="mule-runtime" AND (event_type="process_execution" OR event_type="network_connection")