CVE-2025-13516: File Upload RCE (CVSS 8.1)

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.

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CVSS v3.1 Score

8.1

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Weakness Type (CWE)

CWE-434 Unrestricted Upload

References

Other References

https://cwe.mitre.org/data/definitions/434.html https://plugins.trac.wordpress.org/browser/suremails/trunk/inc/admin/plugin.php#L407 https://plugins.trac.wordpress.org/browser/suremails/trunk/inc/emails/handler/uploads.php#L113 https://plugins.trac.wordpress.org/browser/suremails/trunk/inc/emails/handler/uploads.php#L231 https://plugins.trac.wordpress.org/changeset/3403145/suremails/trunk?contextall=1&old=3389326&old_path=%2Fsuremails%2Ftrunk https://www.wordfence.com/threat-intel/vulnerabilities/id/f3a20047-a325-4d29-a848-7ffa525d0bad?source=cve

Frequently Asked Questions

What is CVE-2025-13516? +

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. It has a CVSS v3.1 base score of 8.1 (HIGH).

How severe is CVE-2025-13516? +

CVE-2025-13516 has a CVSS v3.1 score of 8.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

How do I check if I'm vulnerable to CVE-2025-13516? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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