Executive Summary

CVE-2026-39554 is an unauthenticated PHP Object Injection vulnerability found in the WordPress Fidalgo Theme versions 1.2.2 and below.

This flaw allows attackers to inject malicious PHP objects without needing to authenticate, potentially enabling code injection, SQL injection, path traversal, denial of service, and other harmful actions if a suitable Property-Oriented Programming (POP) chain exists.

It is classified under the OWASP Top 10 category A3: Injection and has a high severity score of 8.1, indicating it is highly dangerous and could be exploited on a large scale.

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Impact Analysis

This vulnerability can have severe impacts including unauthorized code execution, data breaches through SQL injection, unauthorized file access via path traversal, and denial of service attacks.

Because it requires no authentication to exploit, attackers can remotely and easily target vulnerable websites, potentially compromising thousands of sites.

Such exploitation can lead to loss of data integrity, confidentiality, and availability, severely affecting the security and functionality of affected systems.

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Mitigation Strategies

Immediate action is advised to mitigate the PHP Object Injection vulnerability in Fidalgo versions 1.2.2 and below.

• Update the WordPress Fidalgo Theme to version 1.3 or later, which contains the patch for this vulnerability.
• If updating immediately is not possible, apply mitigation measures provided by Patchstack to block attacks targeting this vulnerability.

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Compliance Impact

The vulnerability in the WordPress Fidalgo Theme (versions 1.2.2 and below) is a high-severity PHP Object Injection flaw that can lead to code injection, SQL injection, path traversal, denial of service, and other malicious activities.

Such exploitation risks compromising the confidentiality, integrity, and availability of data, which are core principles in compliance frameworks like GDPR and HIPAA.

If exploited, this vulnerability could lead to unauthorized access or data breaches, potentially causing non-compliance with these regulations due to failure to protect personal or sensitive information.

Therefore, organizations using affected versions should promptly update or mitigate the vulnerability to maintain compliance with common security standards and regulations.

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