Adobe ColdFusion Improper Input Validation Vulnerability (CVE-2026-27306)

Adobe ColdFusion versions 2023.18, 2025.6, and earlier are susceptible to an improper input validation vulnerability identified as CVE-2026-27306. Successful exploitation of this vulnerability allows an attacker with elevated privileges to execute arbitrary code within the context of the current user. The attack necessitates user interaction, specifically the opening of a malicious file crafted by the attacker. This vulnerability poses a risk to organizations utilizing affected ColdFusion versions, as it could lead to compromised systems and data if exploited successfully. Defenders need to ensure that their systems are up to date to mitigate this risk.

Attack Chain

1. The attacker identifies a vulnerable ColdFusion server running a version prior to 2023.18 or 2025.6.
2. The attacker crafts a malicious file designed to exploit the improper input validation vulnerability (CVE-2026-27306). This file could be any format handled by ColdFusion that allows for input validation flaws, like a .cfm or .cfc file.
3. The attacker social engineers a user with elevated privileges to download and open the malicious file.
4. When the user opens the file, ColdFusion processes it, triggering the input validation vulnerability.
5. The improper input validation allows the attacker to inject arbitrary code into the ColdFusion process.
6. The injected code executes within the context of the user who opened the file, granting the attacker the same privileges.
7. The attacker can then use this access to install malware, steal sensitive data, or further compromise the system.

Impact

Successful exploitation of CVE-2026-27306 allows an attacker with elevated privileges to achieve arbitrary code execution. The attacker gains access to the system with the privileges of the user who opened the malicious file. This could lead to the compromise of sensitive data, the installation of backdoors, or the complete takeover of the ColdFusion server. While the number of victims and specific sectors targeted are not specified in the provided context, any organization using a vulnerable version of ColdFusion is at risk.

Recommendation

• Apply the security patch provided by Adobe to address CVE-2026-27306 on all ColdFusion servers. Refer to the advisory link in the references section.
• Implement user training to educate privileged users about the risks of opening files from untrusted sources to mitigate the user interaction requirement of the exploit.
• Enable and review ColdFusion logs for suspicious activity related to file processing or code execution, which could indicate exploitation attempts.
• Deploy the Sigma rules in this brief to your SIEM to detect exploitation attempts.