CVE-2026-27304: Adobe ColdFusion RCE Vulnerability

CVE-2026-27304 Overview

CVE-2026-27304 is a critical Improper Input Validation vulnerability affecting Adobe ColdFusion versions 2023.18, 2025.6, and earlier. This vulnerability enables arbitrary code execution in the context of the current user without requiring any user interaction. The flaw exists in how ColdFusion processes and validates input data, allowing attackers with adjacent network access to execute malicious code on vulnerable systems.

Critical Impact

This vulnerability allows unauthenticated attackers on an adjacent network to achieve arbitrary code execution without user interaction, potentially leading to complete system compromise, data exfiltration, and lateral movement within enterprise environments.

Affected Products

• Adobe ColdFusion 2023 (all updates through Update 18)
• Adobe ColdFusion 2025 (all updates through Update 6)
• Adobe ColdFusion 2023 base installation and all prior updates

Discovery Timeline

• April 14, 2026 - CVE-2026-27304 published to NVD
• April 16, 2026 - Last updated in NVD database

Technical Details for CVE-2026-27304

Vulnerability Analysis

This vulnerability stems from improper input validation (CWE-20) within Adobe ColdFusion's request processing mechanisms. When the application fails to properly validate user-supplied input, attackers can craft malicious requests that bypass security controls and inject executable code. The vulnerability is particularly concerning because it requires no authentication or user interaction to exploit, meaning automated attacks are feasible.

The attack is limited to adjacent network access, which means the attacker must be on the same network segment as the vulnerable ColdFusion server. This could include scenarios such as compromised internal workstations, rogue devices on corporate networks, or attackers who have gained initial access to a network segment hosting ColdFusion infrastructure.

Successful exploitation results in arbitrary code execution running with the privileges of the ColdFusion service account, which typically has elevated permissions for web application operations. This can lead to complete confidentiality and integrity compromise of the affected system.

Root Cause

The root cause of CVE-2026-27304 is an Improper Input Validation weakness (CWE-20) in Adobe ColdFusion. The application fails to adequately sanitize or validate input data before processing it, allowing specially crafted malicious input to be interpreted as executable code. This type of vulnerability often occurs when input is passed to dangerous functions without proper boundary checking, encoding, or type validation.

Attack Vector

The attack vector for this vulnerability is via adjacent network access. An attacker positioned on the same network segment as the vulnerable ColdFusion server can send specially crafted requests to exploit the improper input validation flaw. The attack does not require authentication, does not need user interaction, and has low complexity to execute. Upon successful exploitation, the scope is changed, meaning the vulnerability can affect resources beyond the vulnerable component, with high impact to both confidentiality and integrity.

The attack flow typically involves:

1. Attacker gains access to the adjacent network containing the ColdFusion server
2. Attacker identifies vulnerable ColdFusion instances through service enumeration
3. Malicious payloads are crafted to exploit the input validation weakness
4. Requests containing the payload are sent to the vulnerable application
5. The improperly validated input results in arbitrary code execution

Detection Methods for CVE-2026-27304

Indicators of Compromise

• Unusual process spawning from ColdFusion service processes (coldfusion.exe or related Java processes)
• Unexpected network connections originating from the ColdFusion server to external or internal destinations
• Anomalous file system activity in ColdFusion installation directories or temporary folders
• Evidence of command execution artifacts in ColdFusion logs or Windows Event Logs

Detection Strategies

• Deploy network intrusion detection signatures to identify exploitation attempts targeting ColdFusion input validation flaws
• Monitor ColdFusion application logs for malformed requests, unusual parameter values, or error patterns indicative of exploitation attempts
• Implement endpoint detection rules to alert on suspicious child process creation from ColdFusion service accounts
• Use file integrity monitoring on critical ColdFusion configuration and application files

Monitoring Recommendations

• Enable verbose logging in ColdFusion Administrator and forward logs to a centralized SIEM for correlation
• Monitor for lateral movement indicators following any suspected ColdFusion compromise
• Establish baseline behavior for ColdFusion servers and alert on deviations in network traffic patterns or resource utilization
• Regularly audit ColdFusion server configurations and access control lists for unauthorized changes

How to Mitigate CVE-2026-27304

Immediate Actions Required

• Apply the security updates provided by Adobe as referenced in security bulletin APSB26-38 immediately
• Isolate vulnerable ColdFusion servers from untrusted network segments until patches can be applied
• Review network segmentation to limit adjacent network access to only authorized systems
• Implement web application firewall rules to filter potentially malicious input patterns

Patch Information

Adobe has released security updates to address this vulnerability. Organizations should apply the patches referenced in the Adobe ColdFusion Security Advisory (APSB26-38) immediately. For ColdFusion 2023, upgrade to the version newer than Update 18. For ColdFusion 2025, upgrade to the version newer than Update 6.

It is critical to test patches in a staging environment before deploying to production, but given the critical severity of this vulnerability and the lack of required user interaction, expedited patching is strongly recommended.

Workarounds

• Implement strict network segmentation to prevent untrusted systems from having adjacent network access to ColdFusion servers
• Configure host-based firewalls to restrict inbound connections to ColdFusion only from known, trusted IP addresses
• Deploy a reverse proxy or web application firewall in front of ColdFusion to inspect and filter malicious requests
• If ColdFusion services are not required, consider disabling or shutting down the service until patches can be applied

# Network isolation example - restrict ColdFusion access via iptables
# Allow only specific trusted subnets to access ColdFusion ports
iptables -A INPUT -p tcp --dport 8500 -s 10.10.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8500 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 10.10.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP