CVE-2026-118064: Critical Vulnerability in Advance Guest Post WordPress Plugin

Introduction

The CVE-2026-118064 vulnerability affects the Advance Guest Post WordPress plugin, allowing unauthenticated users to upload malicious PHP files. This flaw can lead to remote code execution, posing a significant risk to the security of WordPress installations using this plugin.

What happened?

The Advance Guest Post plugin, up to version 1.9, does not properly restrict or validate file uploads. The flaw lies in authorizing an upload action with a nonce that is exposed to all front-end visitors. Additionally, file validation is done only based on the leading bytes, allowing unauthenticated users to upload arbitrary PHP files.

How does the vulnerability work?

This vulnerability allows an unauthenticated attacker to upload PHP files that can be executed remotely. Successful exploitation of this flaw requires the target to be running PHP 7.x, as in PHP 8.0 and later, the vulnerable code path raises a fatal error before the file is written.

What is the real impact?

Exploitation of this vulnerability can allow an attacker to execute malicious code on the server, leading to significant security compromises, such as gaining full control over the affected site, stealing sensitive data, or using the server for malicious activities.

Which versions are affected?

• Advance Guest Post up to version 1.9

How to fix

1. Update the Advance Guest Post plugin to the latest available version.
2. Check for other known vulnerabilities in installed plugins and themes.
3. Implement additional security practices, such as using firewalls and monitoring for suspicious activities.

Mitigation while you update

While it is not possible to update, it is recommended to deactivate the Advance Guest Post plugin to avoid any risks associated with this vulnerability. Additionally, it is advisable to monitor server logs for any suspicious activity related to file uploads.

Conclusion

The CVE-2026-118064 vulnerability poses a significant risk to users of the Advance Guest Post plugin. It is crucial for site administrators to take immediate action to address this flaw and protect their WordPress installations.