The vulnerability CVE-2026-22503 affects ThemeREX Nelson (up to version 1.2.0) and is caused by improper validation or control of filenames used in PHP include or require statements. This allows an attacker to perform Local File Inclusion (LFI), which can lead to disclosure of sensitive files or execution of arbitrary code depending on the context. The CVSS v3.1 base score is 8.1, indicating high severity, with network attack vector, high attack complexity, no privileges required, no user interaction, and impacts on confidentiality, integrity, and availability.

Successful exploitation of this vulnerability can lead to full compromise of the affected system's confidentiality, integrity, and availability. An attacker could include local files on the server, potentially exposing sensitive information or executing malicious code. The high CVSS score reflects the significant risk posed by this vulnerability.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no patch or official fix information is provided, users should monitor ThemeREX communications for updates. Until a fix is available, consider restricting access to the affected application and applying any available workarounds recommended by the vendor.