CVE-2025-22800: Post SMTP Auth Bypass Vulnerability

CVE-2025-22800 Overview

CVE-2025-22800 is a missing authorization vulnerability in the Post SMTP plugin for WordPress, developed by Saad Iqbal and maintained by Wpexperts. The flaw stems from incorrectly configured access control security levels, allowing authenticated users to invoke plugin functions they should not be able to reach. The issue affects all Post SMTP versions up to and including 2.9.11. Because the plugin handles outbound mail configuration and message logs, exploitation can expose sensitive credentials and message contents. The vulnerability is tracked under CWE-862: Missing Authorization and was published to the National Vulnerability Database on January 13, 2025.

Critical Impact
A low-privilege authenticated WordPress user can bypass access controls in Post SMTP to compromise the confidentiality, integrity, and availability of mail configuration and message data.

Affected Products

Post SMTP plugin for WordPress, versions up to and including 2.9.11
WordPress sites using the Wpexperts post_smtp component
Any environment where untrusted authenticated users have WordPress accounts on a vulnerable site

Discovery Timeline

2025-01-13 - CVE-2025-22800 published to NVD
2026-04-23 - Last updated in NVD database

Technical Details for CVE-2025-22800

Vulnerability Analysis

The Post SMTP plugin exposes administrative functionality through WordPress action handlers and REST endpoints. In versions through 2.9.11, certain handlers fail to enforce capability checks that restrict access to administrators. As a result, authenticated users with low privileges can invoke functions reserved for site operators. The attack requires network access and low privileges, with no user interaction needed. Successful exploitation impacts confidentiality, integrity, and availability of the mail subsystem and any data it processes.

Root Cause

The root cause is broken access control, classified as CWE-862: Missing Authorization. Plugin endpoints rely on incorrectly configured permission callbacks or omit capability validation entirely. WordPress expects developers to gate privileged actions with current_user_can() checks or REST permission_callback functions. When those checks are missing or evaluate access too permissively, subscriber-level accounts can reach administrator-only operations.

Attack Vector

An attacker first obtains any authenticated WordPress account on the target site, such as a subscriber created through open registration. The attacker then issues HTTP requests directly to vulnerable Post SMTP endpoints. Because authorization is not enforced, the plugin processes the requests as if they came from a privileged user. The attacker can read or manipulate SMTP configuration, view captured email logs, or alter plugin state. Refer to the Patchstack Vulnerability Advisory for additional technical context.

Detection Methods for CVE-2025-22800

Indicators of Compromise

HTTP requests from low-privilege session cookies to Post SMTP admin-ajax.php actions or REST routes under /wp-json/post-smtp/
Unexpected modifications to SMTP credentials, mailer transport settings, or notification recipients
Access to email logs or message content by accounts that should not have manage_options capability
Outbound test emails or password reset traffic originating from the mail subsystem without administrator activity

Detection Strategies

Audit WordPress access logs for non-administrator users issuing requests to Post SMTP endpoints
Compare the installed plugin version against 2.9.11 and flag any host running an unpatched build
Monitor file integrity of wp-content/plugins/post-smtp/ and configuration entries in wp_options
Correlate WordPress authentication events with plugin configuration changes to identify privilege mismatches

Monitoring Recommendations

Forward WordPress and web server logs to a centralized analytics platform for retention and correlation
Alert on changes to SMTP host, port, username, or API key values stored by the plugin
Track creation of new WordPress users followed shortly by requests to plugin administration routes
Review outbound mail volume for anomalies that suggest abuse of the configured transport

How to Mitigate CVE-2025-22800

Immediate Actions Required

Update the Post SMTP plugin to a release later than 2.9.11 as soon as the vendor patch is available
Disable the plugin on sites where an immediate update is not feasible and switch to an alternative mailer
Rotate SMTP credentials, API keys, and any service account passwords that were stored in the plugin configuration
Review WordPress user accounts and remove or downgrade any unexpected registrations

Patch Information

Wpexperts addresses the broken access control issue in releases after Post SMTP 2.9.11. Site operators should consult the Patchstack Vulnerability Advisory for the fixed version reference and apply the update through the WordPress plugin manager or WP-CLI.

Workarounds

Restrict WordPress registration and require administrator approval for new accounts until patched
Place the WordPress admin area behind IP allowlisting or an authenticating reverse proxy
Deploy a Web Application Firewall rule that blocks unauthenticated and low-privilege requests to Post SMTP endpoints
Temporarily replace Post SMTP with a server-level mail relay configured outside of WordPress

bash

# Update Post SMTP using WP-CLI on a vulnerable host
wp plugin update post-smtp --version=latest
wp plugin list --name=post-smtp --fields=name,status,version