CVE-2023-38203: Adobe ColdFusion RCE Vulnerability

CVE-2023-38203 Overview

Adobe ColdFusion versions 2018u17 (and earlier), 2021u7 (and earlier) and 2023u1 (and earlier) are affected by a Deserialization of Untrusted Data vulnerability that could result in Arbitrary code execution. Exploitation of this issue does not require user interaction, making it particularly dangerous for internet-facing ColdFusion installations.

Critical Impact

This vulnerability allows unauthenticated remote attackers to execute arbitrary code on vulnerable Adobe ColdFusion servers without any user interaction. CISA has added this vulnerability to the Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild.

Affected Products

• Adobe ColdFusion 2018 Update 17 and earlier
• Adobe ColdFusion 2021 Update 7 and earlier
• Adobe ColdFusion 2023 Update 1 and earlier

Discovery Timeline

• July 20, 2023 - CVE-2023-38203 published to NVD
• October 23, 2025 - Last updated in NVD database

Technical Details for CVE-2023-38203

Vulnerability Analysis

This insecure deserialization vulnerability in Adobe ColdFusion allows attackers to execute arbitrary code by sending specially crafted serialized data to vulnerable endpoints. The vulnerability stems from the application's failure to properly validate or sanitize untrusted data before deserializing it. When ColdFusion processes malicious serialized objects, attackers can achieve code execution in the context of the ColdFusion service, potentially leading to complete system compromise.

The attack can be executed remotely over the network without requiring any privileges or user interaction. Successful exploitation grants attackers the ability to read, modify, or delete sensitive data, install malware, pivot to other systems on the network, or establish persistent access to the compromised server.

Root Cause

The root cause of CVE-2023-38203 is improper handling of serialized Java objects within Adobe ColdFusion (CWE-502: Deserialization of Untrusted Data). The application deserializes user-controllable data without adequate validation, allowing attackers to inject malicious object graphs that execute arbitrary code during the deserialization process. This class of vulnerability commonly exploits gadget chains present in the application's classpath to achieve code execution.

Attack Vector

The attack is executed over the network against internet-facing or internally accessible ColdFusion servers. Attackers craft malicious serialized payloads containing exploit gadget chains and submit them to vulnerable ColdFusion endpoints. The server processes these payloads without sufficient validation, triggering code execution when the malicious objects are deserialized. No authentication or user interaction is required, making this vulnerability highly exploitable.

The vulnerability mechanism involves crafting malicious serialized Java objects that exploit gadget chains available in the ColdFusion runtime environment. When these objects are deserialized by the vulnerable application, the gadget chain executes attacker-controlled code. For detailed technical information and remediation guidance, refer to the Adobe ColdFusion Security Advisory.

Detection Methods for CVE-2023-38203

Indicators of Compromise

• Unusual outbound network connections from ColdFusion server processes to unknown external IP addresses
• Unexpected child processes spawned by the ColdFusion service (e.g., cmd.exe, powershell.exe, /bin/sh)
• Anomalous serialized data patterns in HTTP request bodies targeting ColdFusion endpoints
• New or modified files in ColdFusion installation directories or web-accessible paths

Detection Strategies

• Monitor HTTP traffic for suspicious serialized Java object signatures (e.g., ac ed 00 05 magic bytes in request bodies)
• Implement Web Application Firewall (WAF) rules to detect and block common Java deserialization exploit patterns
• Deploy endpoint detection and response (EDR) solutions to identify anomalous process behavior from ColdFusion services
• Analyze ColdFusion server logs for unusual error messages related to object deserialization failures

Monitoring Recommendations

• Enable verbose logging on ColdFusion servers and centralize logs for SIEM analysis
• Configure alerts for process execution anomalies originating from the ColdFusion service account
• Monitor network traffic for command-and-control patterns from servers running ColdFusion
• Implement file integrity monitoring on critical ColdFusion directories

How to Mitigate CVE-2023-38203

Immediate Actions Required

• Apply the security patches released by Adobe immediately to all affected ColdFusion installations
• Restrict network access to ColdFusion servers using firewalls and network segmentation
• Review ColdFusion server configurations for unnecessary exposed endpoints
• Conduct incident response activities if exploitation is suspected, including forensic analysis

Patch Information

Adobe has released security updates to address this vulnerability as documented in security bulletin APSB23-41. Organizations should update to the following versions or later:

• ColdFusion 2018 Update 18 or later
• ColdFusion 2021 Update 8 or later
• ColdFusion 2023 Update 2 or later

Due to confirmed active exploitation and inclusion in the CISA Known Exploited Vulnerabilities Catalog, patching should be prioritized as an emergency action.

Workarounds

• If immediate patching is not possible, restrict access to ColdFusion servers to trusted IP addresses only
• Implement strict WAF rules to block serialized Java object payloads in HTTP requests
• Consider temporarily taking vulnerable ColdFusion instances offline until patches can be applied
• Deploy network-based intrusion detection/prevention systems with signatures for Java deserialization attacks

# Example: Restrict ColdFusion access using iptables (Linux)
# Allow access only from trusted management network
iptables -A INPUT -p tcp --dport 8500 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 8500 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP