Executive Summary

CVE-2026-40759 is a high-severity PHP Object Injection vulnerability found in the WordPress Esmée Theme versions 1.4 and below. It allows unauthenticated attackers to inject malicious PHP objects into the application.

This vulnerability can be exploited to perform various malicious actions such as code injection, SQL injection, path traversal, and denial of service, provided a suitable POP (Property Oriented Programming) chain exists.

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Impact Analysis

This vulnerability poses a significant threat as it allows attackers to execute arbitrary code and other malicious activities without authentication.

• Code injection leading to full system compromise.
• SQL injection which can expose or manipulate sensitive data.
• Path traversal attacks that may allow access to restricted files.
• Denial of service attacks that can disrupt website availability.

Because the vulnerability is unauthenticated and can be exploited in mass campaigns targeting thousands of websites, it represents a critical risk to affected sites.

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Mitigation Strategies

Immediate action is required to mitigate the risk posed by the unauthenticated PHP Object Injection vulnerability in Esmée Theme versions 1.4 and below.

• Update the Esmée Theme to version 1.5 or later.
• Apply the mitigation rule provided by Patchstack to block attacks until the update can be applied.

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Compliance Impact

The provided information does not specify how the CVE-2026-40759 vulnerability impacts compliance with common standards and regulations such as GDPR or HIPAA.

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