CVE-2023-29300: Adobe ColdFusion Deserialization of Untrusted Data Vulnerability

CVE-2023-29300 is a deserialization of untrusted data vulnerability in Adobe ColdFusion that allows an attacker to achieve code execution. It matters because successful exploitation can give an adversary control of the ColdFusion host, enabling further lateral movement, data theft, or ransomware deployment. CISA notes known ransomware use of this vulnerability, so organizations running ColdFusion should treat it as a high-priority risk and confirm all details against the vendor advisory.

How it works

The underlying weakness is CWE-502: deserialization of untrusted data. ColdFusion, like many application platforms, can accept serialized objects from clients or other services and reconstruct them in memory. When the application deserializes data without sufficient validation or type restrictions, an attacker can craft a malicious serialized payload that, upon deserialization, triggers unintended code execution on the server.

In practical terms, an unauthenticated or low-privilege attacker who can reach an exposed ColdFusion endpoint that accepts serialized input may be able to supply such a payload and obtain remote code execution under the privileges of the ColdFusion process. Exact attack vectors, required endpoints, and payload formats are not detailed here; defenders must consult the official Adobe advisory for those specifics rather than relying on general descriptions of the class.

Am I affected? How to find it in your systems

Adobe ColdFusion is commonly deployed as a web application server or middleware component that powers dynamic web sites, APIs, and internal business applications. It often runs on Windows or Linux hosts, sometimes behind reverse proxies or load balancers, and may be exposed both internally and to the internet.

• Inventory all servers and containers that host ColdFusion installations, including development, staging, and production instances.
• Query configuration management databases, software asset inventories, and package managers for ColdFusion-related packages or services.
• Check process lists and listening ports for ColdFusion-related binaries or Java processes associated with the product.
• Review which versions and update levels are installed; the precise affected versions must be confirmed against the Adobe advisory, as this guidance does not list them.
• Examine network exposure: identify any ColdFusion administrative or application endpoints reachable from untrusted networks.

For signs of exploitation, look for anomalous process creation under the ColdFusion service account, unexpected outbound connections, or log entries indicating failed or unusual deserialization activity. Correlate web access logs with subsequent host-based indicators of compromise. Because public detail on exact telemetry is limited, treat any unexplained code execution or ransomware activity on ColdFusion hosts as potentially related until ruled out.

How to remediate

The primary remediation is to apply the vendor-supplied update or mitigation instructions for CVE-2023-29300. Follow Adobe’s advisory exactly; do not rely on third-party version lists or unofficial patches. After patching, verify that the update is present and that the service restarts cleanly.

Beyond the specific fix, harden the deserialization surface for this class of vulnerability:

• Ensure ColdFusion is configured to reject or strictly validate untrusted serialized input wherever possible.
• Run the ColdFusion process with least privilege and isolate it from sensitive data stores and other critical systems.
• Disable any unused features, administrative interfaces, or serialization-related endpoints that are not required for business function.
• Keep the underlying operating system and Java runtime fully patched, as they form part of the execution environment.

CISA’s required action is to apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. Document the remediation steps and retain evidence of the applied updates for compliance and incident-response purposes.

If you can't patch immediately

If an immediate patch window is unavailable, implement compensating controls to reduce exposure until the vendor update can be applied:

• Network segmentation: place ColdFusion hosts in a restricted zone with strict ingress and egress filtering; allow only necessary traffic from trusted sources.
• Virtual patching / WAF: deploy web application firewall rules that block or challenge requests containing serialized object patterns or known exploit signatures for this class of flaw; tune carefully to avoid false positives.
• Feature disablement: turn off any non-essential ColdFusion services, remote administration, or endpoints that accept serialized data.
• Enhanced monitoring: enable detailed logging of ColdFusion and host activity, forward logs to a SIEM, and alert on process creation, unusual network connections, or ransomware-related file activity.
• Access controls: enforce multi-factor authentication for any administrative interfaces and restrict management access to jump hosts or bastion networks.

These measures lower risk but do not eliminate it; schedule the official patch as soon as operationally feasible. If mitigations cannot be applied, CISA guidance includes discontinuing use of the product.

If your data may have been exposed

Actively exploited vulnerabilities that enable code execution, especially those with known ransomware use, frequently lead to data breaches or encryption events. If you have evidence of compromise or suspect exposure, initiate your incident-response plan, isolate affected systems, and preserve forensic evidence. As a quick personal check, you can run a free exposure scan of your email address against known breach data sets to determine whether associated credentials or personal information have already appeared in public dumps.