CrushFTP Server-Side Template Injection (SSTI) and Remote Code Execution Vulnerability (CVE-2024-4040) Security Advisory
Executive & SecOps Summary
SECOPS ASSESSMENTAll versions of CrushFTP prior to 10.7.1 and 11.1.0 across all operating system platforms
Unauthenticated remote attackers can bypass the VFS Sandbox, read arbitrary files from the filesystem, bypass authentication to gain administrative access, and execute arbitrary code on the server.
Immediately upgrade CrushFTP to the patched versions (10.7.1 or 11.1.0 or higher) and apply WAF rules to block template injection payloads.
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Immediately upgrade your CrushFTP instance to version 10.7.1 or 11.1.0 (or higher) using the built-in update mechanism or command-line interface.
# Navigate to the CrushFTP installation directory and run the update (Linux example)
cd /var/opt/CrushFTP10/
java -jar CrushFTP.jar -update
# Restart the service to apply the patch
systemctl restart crushftp2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, deploy Web Application Firewall (WAF) rules or reverse proxy configurations to block common template injection patterns.
# Nginx reverse proxy mitigation rule example
server {
listen 80;
server_name crushftp.local;
location / {
# Block requests containing template injection syntax or sensitive file access attempts
if ($request_uri ~* "(\{|\}|\%7B|\%7D|class\.loader|java\.lang)") {
return 403 'Access Denied: Potential Exploit Attempt Blocked';
}
proxy_pass http://127.0.0.1:8080;
}
}3. Log Audit & IoC Verification Commands
Inspect CrushFTP logs for suspicious template syntax or unauthorized attempts to access sensitive XML configuration files.
# Search CrushFTP logs for potential SSTI payloads and VFS bypass attempts
grep -riE "(\{.*\}|\%7B.*\%7D|users\.xml|sessions\.xml)" /var/opt/CrushFTP10/logs/Block Exploits Instantly with Managed Virtual Patching Rules
Can't patch production immediately? Deploy managed WAF rules at the edge to intercept RCE, SQLi, and deserialization payloads before they hit your origin server.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2024-4040) is a critical Server-Side Template Injection (SSTI, CWE-1336) and Code Injection (CWE-94) vulnerability residing in the web interface of CrushFTP. The root cause lies in the improper validation of user-supplied input passed directly into the template rendering engine. This allows unauthenticated remote attackers to inject malicious template expressions, leading to a complete bypass of the Virtual File System (VFS) sandbox restrictions.
2. Exploitation Mechanics & Attack Scenario
An unauthenticated attacker can exploit this vulnerability by sending a crafted HTTP/HTTPS request containing malicious template payloads to the CrushFTP server. The template engine processes this payload, allowing the attacker to read sensitive configuration files (such as 'users.xml' or active session tokens) outside the sandbox. By hijacking administrative sessions or extracting credentials, the attacker can bypass authentication, gain administrative access, and ultimately achieve Remote Code Execution (RCE) under the context of the running service. This vulnerability has been actively exploited in the wild as a zero-day.
3. Infrastructure & Business Impact
With a CVSS score of 10.0 and its inclusion in the CISA KEV (Known Exploited Vulnerabilities) catalog, this vulnerability poses an extreme risk to enterprise infrastructure. Successful exploitation allows complete compromise of the file transfer server, leading to data exfiltration, potential ransomware deployment, and lateral movement within the internal network.
Official Vendor Advisories & References
A server side template injection vulnerability in CrushFTP in all versions before 10.7.1 and 11.1.0 on all platforms allows unauthenticated remote attackers to read files from the filesystem outside of the VFS Sandbox, bypass authentication to gain administrative access, and perform remote code execution on the server.
Frequently Asked SecOps Questions (CVE-2024-4040)
FAQQ1. How critical is CVE-2024-4040 and is it actively exploited in the wild?
CVE-2024-4040 is rated CVSS 10.0 (CRITICAL) with a 30-day EPSS exploitation probability of 99.5%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2024-4040?
Primary impacted vendors include crushftp across crushftp. Scope summary: CrushFTP versions before 10.7.1 and 11.1.0 on all platforms
Q3. What temporary mitigations or workarounds exist for CVE-2024-4040 before patching?
[Mitigation] Immediately upgrade CrushFTP to the patched versions (10.7.1 or 11.1.0 or higher) and apply WAF rules to block template injection payloads. Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2024-4040
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