This vulnerability in Richard Leishman Mail Subscribe List (<= 2.1.10) is a Stored Cross-site Scripting (XSS) issue caused by improper input neutralization during web page generation. An attacker with low privileges and requiring user interaction can inject malicious scripts that persist in the application, potentially impacting confidentiality, integrity, and availability. The CVSS 3.1 base score is 6.5, reflecting a medium severity with network attack vector, low attack complexity, and partial impact on confidentiality, integrity, and availability. No patch or vendor advisory is currently provided.

Successful exploitation allows an attacker to execute arbitrary scripts in the context of the affected web application, potentially leading to partial disclosure of sensitive information, modification of data, or disruption of service. The attack requires user interaction and low privileges, limiting but not negating the risk. No known active exploitation has been reported.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, users should apply general best practices for mitigating XSS vulnerabilities such as input validation and output encoding where possible. Monitor vendor channels for updates and patches.