Based on the description, it is inferred that the WP Mailster plugin for WordPress allows local file inclusion due to improper handling of filenames in its include/require logic. An attacker who can influence the path used for inclusion may read arbitrary files that the web server can access, potentially exposing configuration files, credentials, logs, or other sensitive data. This can further enable privilege escalation or lateral movement if the attacker acquires useful information.

WordPress installations that have installed the WP Mailster plugin with a version up to and including 1.9.1.0 are affected. The issue exists in all releases from the first available release through 1.9.1.0.

Based on the description, it is inferred that the attack vector involves an attacker supplying a crafted filename via a user‑facing parameter to the plugin. The CVSS score of 6.5 indicates a moderate severity, implying that exploitation does not require sophisticated preconditions. EPSS is not available, so the exact likelihood of exploitation cannot be quantified. The vulnerability is not listed in the CISA KEV catalog, suggesting no widespread exploitation has been documented. Typically, an attacker can supply a crafted filename via a user‑facing parameter to the plugin, allowing the inclusion of any file accessible to the web server process, which can result in sensitive data disclosure or further compromise.