CVE-2026-22423 is a Local File Inclusion (LFI) vulnerability found in the Select-Themes SetSail PHP theme, affecting versions up to 1.8. The vulnerability arises from improper control over the filename parameter used in PHP include or require statements, allowing an attacker to manipulate the input to include arbitrary local files on the server. This can lead to unauthorized disclosure of sensitive files such as configuration files, source code, or credentials, and potentially enable remote code execution if combined with other vulnerabilities or writable file uploads. The issue is classified as a PHP Remote File Inclusion type but specifically manifests as Local File Inclusion due to improper input validation. The vulnerability was reserved in early 2026 and published in March 2026, with no CVSS score assigned yet and no known exploits in the wild. The lack of authentication requirement and the ability to influence file inclusion make this vulnerability particularly dangerous in shared hosting or multi-user environments. The affected product, SetSail, is a WordPress theme developed by Select-Themes, commonly used in various websites, which increases the attack surface. The vulnerability underscores the importance of secure coding practices around file inclusion functions in PHP, such as whitelisting allowed files, sanitizing inputs, and avoiding dynamic inclusion of files based on user input.

The primary impact of CVE-2026-22423 is the potential unauthorized disclosure of sensitive information stored on the server, including configuration files, credentials, and source code. This can lead to further attacks such as privilege escalation, remote code execution, or complete system compromise if attackers leverage the disclosed information. The vulnerability undermines the confidentiality and integrity of affected systems. For organizations, this can result in data breaches, service disruptions, reputational damage, and compliance violations. Since the vulnerability does not require authentication or user interaction, it can be exploited remotely by unauthenticated attackers, increasing the risk. Websites using the vulnerable SetSail theme are at risk of being compromised, which can affect e-commerce, content management, and other web services relying on this theme. The scope of affected systems is limited to those running the vulnerable versions of SetSail, but given the popularity of PHP and WordPress themes, the potential impact is significant.

1. Immediately audit all instances of the SetSail theme and identify versions up to 1.8 in use. 2. Apply patches or updates from Select-Themes as soon as they are released addressing this vulnerability. 3. Implement strict input validation and sanitization on all parameters influencing file inclusion, ideally using whitelists of allowed files. 4. Disable dynamic file inclusion based on user input where possible. 5. Configure PHP settings to disable dangerous functions like allow_url_include and restrict file system access using open_basedir. 6. Employ Web Application Firewalls (WAFs) with rules to detect and block attempts to exploit LFI vulnerabilities. 7. Regularly monitor logs for suspicious file inclusion attempts or unusual access patterns. 8. Educate developers on secure coding practices related to file inclusion and input handling. 9. Consider isolating or sandboxing web applications to limit the impact of potential exploitation. 10. Backup critical data regularly to enable recovery in case of compromise.