What the vulnerability does
01Description
The Post SMTP plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 3.6.1. This is due to the plugin not properly verifying that a user is authorized to update OAuth tokens on the 'handle_gmail_oauth_redirect' function. This makes it possible for authenticated attackers, with subscriber level access and above, to inject invalid or attacker-controlled OAuth credentials. CVE-2025-67563 appears to be a duplicate of this issue.
Explanation of Vulnerability in Simple Terms
02Summary
Post SMTP versions up to 3.6.1 lack proper authorization checks, allowing authenticated users with low privileges to modify email settings and disrupt mail delivery. An attacker with a basic user account can alter SMTP configuration, potentially redirecting outgoing emails or causing delivery failures. Site administrators should update to a version newer than 3.6.1 and review email settings after patching.
What an attacker can do
03Attacker Capabilities
Modify SMTP settings and disrupt email delivery with a low-privilege user account.
Potential impact on your site
04Site Impact
Email delivery may be disrupted or redirected; attackers can alter SMTP configuration without admin approval.
Conditions required to exploit
05Prerequisites
Attacker must have a low-privilege user account on the WordPress site; no special user interaction required.
Key dates
06Disclosure timeline
December 3, 2025
CVE published
April 8, 2026
Record updated
