Adobe ColdFusion Deserialization Remote Code Execution (RCE) Security Advisory (CVE-2018-4939)
Executive & SecOps Summary
SECOPS ASSESSMENTAdobe ColdFusion 2016 Update 5 and earlier, ColdFusion 11 Update 13 and earlier
Unauthenticated remote attackers can execute arbitrary code with system privileges by exploiting a deserialization of untrusted data (CWE-502)
Immediately apply the official Adobe security patch (APSB18-14) and restrict external access to RMI and management ports
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Apply the official security update via the ColdFusion Administrator Console. For manual command-line installation, use the following steps:
# Stop ColdFusion service and apply the hotfix jar (Example for ColdFusion 2016)
cd /opt/coldfusion2016/cfusion/bin
./coldfusion stop
# Download and execute the hotfix installer
wget https://cfdownload.adobe.com/pub/adobe/coldfusion/2016/hotfix_014.jar
java -jar hotfix_014.jar
./coldfusion start2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, block external access to the RMI port and restrict access to the ColdFusion Administrator interface.
# Block external access to the default RMI port (1099) using iptables
sudo iptables -A INPUT -p tcp --dport 1099 -j DROP
# Allow access only from a trusted administration subnet
sudo iptables -I INPUT -p tcp -s 192.168.1.100 --dport 1099 -j ACCEPT3. Log Audit & IoC Verification Commands
Verify the running ports and check the update history to ensure the system is not running a vulnerable version.
# Check if the RMI port is listening and exposed
netstat -an | grep 1099
# Inspect the ColdFusion update history log for applied hotfixes
cat /opt/coldfusion2016/cfusion/hf-updates/updates.xml | grep -i 'version'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-2018-4939) is a critical remote code execution (RCE) flaw in Adobe ColdFusion caused by the deserialization of untrusted data (CWE-502). The root cause lies in the application's failure to properly validate or filter serialized Java objects sent to specific endpoints, such as the Java Remote Method Invocation (RMI) registry or web service interfaces, before deserializing them.
2. Exploitation Mechanics & Attack Scenario
An attacker targets the Java RMI port (typically port 1099) or HTTP endpoints that accept serialized objects. By utilizing tools like ysoserial to construct a malicious payload containing a gadget chain (e.g., Apache Commons Collections), the attacker transmits the payload to the vulnerable ColdFusion server. Upon deserialization, the payload triggers arbitrary OS command execution in the context of the ColdFusion process.
3. Infrastructure & Business Impact
With a CVSS 3.1 score of 9.8 (Critical) and its inclusion in the CISA KEV catalog, this vulnerability represents a severe threat that has been actively exploited in the wild. Successful exploitation allows complete system compromise, enabling attackers to establish persistence, pivot within the internal network, exfiltrate sensitive data, or deploy ransomware.
Official Vendor Advisories & References
Adobe ColdFusion Update 5 and earlier versions, ColdFusion 11 Update 13 and earlier versions have an exploitable Deserialization of Untrusted Data vulnerability. Successful exploitation could lead to arbitrary code execution.
Frequently Asked SecOps Questions (CVE-2018-4939)
FAQQ1. How critical is CVE-2018-4939 and is it actively exploited in the wild?
CVE-2018-4939 is rated CVSS 9.8 (CRITICAL) with a 30-day EPSS exploitation probability of 61.8%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2018-4939?
Primary impacted vendors include adobe across coldfusion. Scope summary: Adobe ColdFusion 2016 Update 5 and earlier, ColdFusion 11 Update 13 and earlier
Q3. What temporary mitigations or workarounds exist for CVE-2018-4939 before patching?
[Mitigation] Immediately apply the official Adobe security patch (APSB18-14) and restrict external access to RMI and management ports Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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