The vulnerability CVE-2026-57803 in Select-Themes Struktur Core arises from improper control of the filename parameter in PHP include/require statements, enabling PHP Local File Inclusion. This flaw affects Struktur Core versions up to 2.5.1. The CVSS 3.1 base score is 7.5, indicating high severity, with network attack vector, high complexity, low privileges required, no user interaction, and impacts on confidentiality, integrity, and availability. No official patch or remediation guidance is currently available from the vendor or advisory sources.

Successful exploitation of this vulnerability could allow an attacker to include local files on the server, potentially leading to disclosure of sensitive information, code execution, or denial of service. The CVSS score reflects high impact on confidentiality, integrity, and availability.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, review and restrict access to the affected application and consider applying temporary mitigations such as input validation or disabling vulnerable functionality if feasible.