SureMail – SMTP and Email Logs Plugin with Amazon SES, Postmark, and Other Providers <= 1.9.0 - Unauthenticated Arbitrary File Upload

Unrestricted Upload of File with Dangerous Type
CVE CVE-2025-13516
CVSS High (8.1)
Publicly Published December 1, 2025
Last Updated December 2, 2025
Researcher type5afe
Description

The SureMail – SMTP and Email Logs Plugin for WordPress is vulnerable to Unrestricted Upload of File with Dangerous Type in versions up to and including 1.9.0. This is due to the plugin's save_file() function in inc/emails/handler/uploads.php which duplicates all email attachments to a web-accessible directory (wp-content/uploads/suremails/attachments/) without validating file extensions or content types. Files are saved with predictable names derived from MD5 hashes of their content. While the plugin attempts to protect this directory with an Apache .htaccess file to disable PHP execution, this protection is ineffective on nginx, IIS, and Lighttpd servers, or on misconfigured Apache installations. This makes it possible for unauthenticated attackers to achieve Remote Code Execution by uploading malicious PHP files through any public form that emails attachments, calculating the predictable filename, and directly accessing the file to execute arbitrary code granted they are exploiting a site running on an affected web server configuration.

References

1 affected software package

Software Type Plugin
Software Slug suremails (view on wordpress.org)
Patched? Yes
Affected Version
  • <= 1.9.0
Patched Version
  • 1.9.1
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