The vulnerability CVE-2026-28055 in ThemeREX M.Williamson arises from improper control of the filename parameter used in PHP include or require statements, leading to a Local File Inclusion (LFI) vulnerability. This allows an attacker to include files on the server, potentially exposing sensitive information or enabling further code execution. The issue affects all versions up to 1.2.11. The CVSS v3.1 base score is 8.1, indicating a high severity with network attack vector, high attack complexity, no privileges required, no user interaction, and impacts on confidentiality, integrity, and availability. No patch or vendor advisory is currently available to confirm remediation status.

Successful exploitation of this vulnerability could allow an attacker to include local files on the server, potentially leading to disclosure of sensitive information, modification of application behavior, or denial of service. The CVSS score of 8.1 reflects a high impact on confidentiality, integrity, and availability. There are no known exploits in the wild, but the vulnerability poses a significant risk if left unaddressed.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, users should consider restricting access to vulnerable endpoints, applying web application firewall rules to detect and block malicious input targeting file inclusion, and monitoring for suspicious activity related to file inclusion attempts. Avoid exposing the application to untrusted networks if possible.