CVE-2023-29300: Adobe ColdFusion RCE Vulnerability

CVE-2023-29300 Overview

CVE-2023-29300 is a critical Insecure Deserialization vulnerability affecting Adobe ColdFusion that allows remote attackers to execute arbitrary code on vulnerable systems. The flaw stems from the unsafe handling of serialized data, enabling attackers to craft malicious payloads that, when deserialized by the application, result in code execution with the privileges of the ColdFusion service. This vulnerability requires no user interaction and can be exploited remotely over the network, making it particularly dangerous for internet-facing ColdFusion installations.

Critical Impact

This vulnerability has been added to CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating active exploitation in the wild. Organizations running vulnerable Adobe ColdFusion versions should prioritize immediate patching.

Affected Products

• Adobe ColdFusion 2018 Update 16 and earlier
• Adobe ColdFusion 2021 Update 6 and earlier
• Adobe ColdFusion 2023.0.0.330468 and earlier

Discovery Timeline

• July 12, 2023 - CVE-2023-29300 published to NVD
• October 23, 2025 - Last updated in NVD database

Technical Details for CVE-2023-29300

Vulnerability Analysis

This vulnerability is classified as CWE-502: Deserialization of Untrusted Data. The weakness exists in how Adobe ColdFusion processes serialized Java objects from untrusted sources. When the application deserializes attacker-controlled data without proper validation, it allows the execution of arbitrary code in the context of the ColdFusion application server.

Deserialization vulnerabilities in Java-based applications like ColdFusion are particularly severe because the Java serialization mechanism can be abused to instantiate arbitrary objects and invoke methods during the deserialization process. Attackers leverage "gadget chains" — sequences of existing classes within the application's classpath that can be chained together to achieve code execution.

Root Cause

The root cause of CVE-2023-29300 lies in Adobe ColdFusion's failure to adequately validate or sanitize serialized data before processing it. The application accepts serialized Java objects from network requests without implementing proper deserialization controls such as:

• Allowlisting of permitted classes for deserialization
• Input validation of serialized data streams
• Isolation of the deserialization context

This allows attackers to submit malicious serialized objects that, when processed by the vulnerable deserialization routines, trigger arbitrary code execution through the exploitation of available gadget chains in the ColdFusion classpath.

Attack Vector

The attack is executed remotely over the network without requiring authentication or user interaction. An attacker can craft a specially constructed HTTP request containing a malicious serialized Java object payload. When the ColdFusion server processes this request and deserializes the payload, the embedded gadget chain executes arbitrary commands with the privileges of the ColdFusion service account.

The exploitation flow typically involves:

1. Identifying a vulnerable ColdFusion endpoint that processes serialized data
2. Generating a malicious serialized payload using tools that leverage known gadget chains
3. Sending the payload to the target server via an HTTP request
4. The server deserializes the malicious payload, triggering code execution

Due to the nature of deserialization vulnerabilities, exploitation does not require valid credentials or user interaction, making automated mass exploitation feasible.

Detection Methods for CVE-2023-29300

Indicators of Compromise

• Unusual outbound network connections from ColdFusion server processes to unknown external IP addresses
• Presence of unexpected web shells or backdoors in ColdFusion web directories (e.g., .cfm, .cfc files with suspicious content)
• Anomalous process spawning from the ColdFusion Java process, particularly command shells or scripting interpreters
• Evidence of serialized Java object payloads in HTTP request logs, identifiable by aced0005 magic bytes in Base64-encoded or raw form

Detection Strategies

• Implement network-level monitoring for suspicious traffic patterns to and from ColdFusion servers, particularly unusual POST requests with binary payloads
• Deploy web application firewall (WAF) rules to detect and block common Java deserialization attack signatures
• Enable detailed logging on ColdFusion servers and forward logs to a SIEM for correlation and analysis
• Conduct regular file integrity monitoring on ColdFusion installation directories to detect unauthorized modifications

Monitoring Recommendations

• Monitor ColdFusion application logs for exceptions related to deserialization or class loading errors, which may indicate exploitation attempts
• Implement endpoint detection and response (EDR) solutions to identify and alert on suspicious process behavior originating from the ColdFusion service
• Establish baseline network behavior for ColdFusion servers and alert on deviations that could indicate compromise

How to Mitigate CVE-2023-29300

Immediate Actions Required

• Apply Adobe's security update (APSB23-40) immediately to all affected ColdFusion installations
• If immediate patching is not possible, restrict network access to ColdFusion servers using firewall rules to limit exposure
• Review ColdFusion servers for signs of compromise before and after patching, as this vulnerability has been actively exploited
• Ensure ColdFusion is not running with elevated privileges; use a dedicated service account with minimal required permissions

Patch Information

Adobe has released security updates to address this vulnerability in security bulletin APSB23-40. Organizations should update to the following patched versions:

• ColdFusion 2018 Update 17 or later
• ColdFusion 2021 Update 7 or later
• ColdFusion 2023 Update 1 or later

Due to the critical severity and confirmed active exploitation, CISA has added CVE-2023-29300 to its Known Exploited Vulnerabilities Catalog, mandating federal agencies to remediate the vulnerability within specified timelines.

Workarounds

• Implement network segmentation to isolate ColdFusion servers from direct internet access, using a reverse proxy or load balancer to filter traffic
• Deploy a web application firewall (WAF) with rules specifically designed to detect Java deserialization attack payloads
• If feasible, disable or restrict access to endpoints that process serialized data until patches can be applied
• Consider implementing Java agent-based deserialization protections that can block dangerous gadget chains at runtime

# Example: Restrict access to ColdFusion Admin using iptables
# 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

# Block external access to ColdFusion while allowing internal traffic
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT