Post SMTP WordPress Plugin XSS Vulnerabilities

A stored cross-site scripting (XSS) vulnerability exists in the Post SMTP WordPress plugin through version 3.8.0, allowing unauthenticated attackers to inject malicious scripts via the 'event_type' parameter. The vulnerability requires the Post SMTP Pro plugin with its Reporting and Tracking extension to be enabled for exploitation. With a CVSS score of 7.2 and unauthenticated network-based exploitation possible, this represents a moderate-to-high severity risk for WordPress sites using both the free and Pro versions of Post SMTP together.

The Post SMTP WordPress plugin for versions up to 3.8.0 contains an authorization bypass vulnerability in the Office 365 OAuth redirect handler that allows authenticated subscribers and above to overwrite sensitive SMTP configuration without proper capability checks or nonce validation. An attacker with subscriber-level access can craft a malicious URL to inject attacker-controlled Azure app credentials into the site's Microsoft 365 configuration, potentially causing administrators to unknowingly connect to the attacker's account during Pro wizard setup. This vulnerability has a CVSS score of 5.3 and is classified as CWE-862 (Missing Authorization), with active evidence of the vulnerable code path present in the plugin repository.