What the vulnerability does
01Description
The Post SMTP plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the `handle_office365_oauth_redirect()` function in all versions up to, and including, 3.8.0. This is due to the function being hooked to `admin_init` without any `current_user_can()` check or nonce verification. This makes it possible for authenticated attackers, with Subscriber-level access and above, to overwrite the site's Office 365 OAuth mail configuration (access token, refresh token, and user email) via a crafted URL. The configuration option is used during wizard setup of Microsoft365 SMTP, only available in the Pro option of the plugin. This could cause an Administrator to believe an attacker-controlled Azure app is their own, and lead them to connect the plugin to the attacker's account during configuration after upgrading to Pro.
Explanation of Vulnerability in Simple Terms
02Summary
Post SMTP versions up to 3.8.0 lack proper authorization checks, allowing authenticated users with low privileges to modify email settings or configuration without proper permission verification. The vulnerability requires network access and low-level authentication but does not require user interaction. Integrity of email delivery settings can be compromised.
What an attacker can do
03Attacker Capabilities
Modify email configuration or SMTP settings without proper authorization.
Potential impact on your site
04Site Impact
Unauthorized users could alter email delivery settings, potentially disrupting email functionality or redirecting messages.
Conditions required to exploit
05Prerequisites
Attacker must have low-level authenticated access to the WordPress site.
Key dates
06Disclosure timeline
March 18, 2026
CVE published
April 8, 2026
Record updated
