The Avada theme for WordPress is vulnerable to Arbitrary File Write in all versions up to, and including, 7.16 when the Fusion Builder plugin is installed and active in versions up to, and including, 3.16. This is due to a chain of authorization and input validation weaknesses across the two components that makes it possible for unauthenticated attackers to write attacker-controlled files to the server. This can be used to create and execute arbitrary PHP files, resulting in remote code execution and complete site compromise. Successful exploitation requires both Avada and Fusion Builder to be installed and active, as well as certain administrator-authored content to be present.

A critical vulnerability (CVE-2026-18431) affects the Avada theme for WordPress in versions up to and including 7.16, when used in conjunction with the Fusion Builder plugin (versions up to and including 3.16). The flaw stems from a chain of authorization and input validation weaknesses across both components, allowing unauthenticated attackers to write arbitrary files to the server. Successful exploitation enables the creation and execution of arbitrary PHP files, leading to remote code execution (RCE) and complete site compromise. Exploitation requires both Avada and Fusion Builder to be installed and active, along with certain administrator-authored content being present on the site. The vulnerability is classified as high severity due to its unauthenticated attack vector and potential for full system compromise. Users are advised to update to patched versions of both the Avada theme and Fusion Builder plugin immediately.