Executive Summary

CVE-2026-39539 is a high-priority PHP Object Injection vulnerability found in the WordPress theme "Alloggio - Hotel Booking Theme" version 2.1.2 or earlier.

This vulnerability allows unauthenticated attackers to inject malicious PHP objects, potentially leading to code execution, SQL injection, path traversal, denial of service, and other harmful actions if a suitable POP (Property Oriented Programming) chain exists.

It is classified under OWASP Top 10 A3: Injection and can be exploited without any authentication.

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Impact Analysis

This vulnerability can have severe impacts including unauthorized code execution, which may allow attackers to take control of the affected website.

It can also lead to SQL injection, enabling attackers to manipulate or steal data from the database.

Other possible impacts include path traversal attacks, denial of service conditions, and other malicious activities that compromise the security and availability of the website.

Given the high CVSS score of 8.1, this vulnerability poses a significant risk and could be exploited in mass campaigns targeting thousands of websites.

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Detection Guidance

The vulnerability is an unauthenticated PHP Object Injection in the Alloggio - Hotel Booking Theme version 2.1.2 or earlier. Detection involves monitoring for exploitation attempts targeting this theme, especially looking for suspicious HTTP requests that may attempt code injection, SQL injection, or path traversal.

Patchstack has provided a mitigation rule to block attacks until the update is applied, which implies that network-based detection can be done by applying such rules in web application firewalls or intrusion detection systems.

Specific commands are not provided in the available resources, but typical detection methods include inspecting web server logs for unusual POST or GET requests containing serialized PHP objects or payloads attempting injection.

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Mitigation Strategies

Immediate mitigation steps include updating the Alloggio - Hotel Booking Theme to version 2.1.3 or later, where the vulnerability has been patched.

Until the update can be applied, it is recommended to implement the mitigation rule provided by Patchstack to block attack attempts targeting this vulnerability.

Additionally, seeking assistance from hosting providers or developers to apply these mitigations and monitor for exploitation attempts is advised.

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Compliance Impact

The vulnerability allows unauthenticated PHP Object Injection which can lead to code injection, SQL injection, path traversal, denial of service, and other malicious activities. Such exploitation could result in unauthorized access, data breaches, or service disruptions.

These impacts can compromise the confidentiality, integrity, and availability of data, potentially violating compliance requirements under standards like GDPR and HIPAA that mandate protection of personal and sensitive information.

Therefore, failure to patch this vulnerability or mitigate its exploitation could lead to non-compliance with these regulations due to increased risk of data breaches and unauthorized data manipulation.

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