External risk intelligence

Anesta Theme PHP Object Injection Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-66567

The vulnerability affects a WordPress theme, which is a component of a web application. WordPress sites are frequently deployed as public-facing web services, making the application's components, including themes that process user requests, commonly reachable via the public internet.

Deserialization

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This advisory concerns a critical security flaw in a widely used web technology, specifically Anesta themes up to version 1.5.3, which could allow unauthorized individuals to inject malicious code. The underlying issue is an unauthenticated PHP object injection, meaning an attacker could potentially compromise systems without needing any login credentials. This type of vulnerability could lead to significant data breaches or service disruptions, underscoring the importance of assessing its presence within our digital infrastructure.

Unauthenticated code injection in a web theme.
Critical flaw could allow unauthorized access.
Confirm relevance and exposure of the theme.

Attack Path

How an attacker could exploit the issue

An attacker can exploit an unauthenticated PHP object injection vulnerability in Anesta themes to execute arbitrary code. This occurs when the theme processes serialized PHP data without proper validation, allowing an attacker to inject malicious objects that can lead to severe system compromise.

No authentication required to start.
User-provided data triggers vulnerability.
Complete system compromise is possible.

Live Threat

Current exploitation, exposure, and threat context

A PHP Object Injection vulnerability in Anesta, when the advisory conditions are met, could allow an unauthenticated attacker to inject malicious PHP objects. This could potentially lead to the execution of arbitrary code or unauthorized modification of data handled by the affected system. The impact depends on how the application deserializes untrusted data and the privileges of the running process.

System data and sensitive information.
Unauthenticated remote code execution.
Compromise of system integrity.

Operational Fix

Recommended remediation, mitigation, and detection steps

This unauthenticated PHP Object Injection vulnerability in Anesta affects web applications. Platform or application owners are likely responsible for addressing this, in coordination with security teams if the affected component is externally accessible. The first practical step is to locate all instances of Anesta and assess their reachability and business criticality to prioritize remediation efforts.

Application owners should lead remediation.
Verify Anesta presence and exposure.
Plan and execute risk-based remediation.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is the Anesta theme used for in web applications?

Anesta is a WordPress theme, which serves as a foundational component for controlling the visual layout and user interface of a website. It manages how content is presented to visitors and often handles server-side data processing tasks behind the scenes to support the site's functionality.

What does PHP Object Injection mean for CVE-2026-66567?

This vulnerability is classified as CWE-502, Deserialization of Untrusted Data. It means the software accepts specially crafted, malicious data and reconstructs it into a PHP object without safety checks. Because the code trusts this input, an attacker can manipulate these objects to execute unintended commands or compromise system data.

How does an attacker trigger this vulnerability?

The flaw is triggered when the theme processes serialized data provided by a user. Since it is unauthenticated, no login or administrative rights are needed; the system simply accepts the malicious payload as if it were legitimate. It is not triggered by static site content that does not involve user-submitted data processing.

Is my site at risk according to Halo Surface Signal?

Halo Surface Signal identifies that because Anesta is a WordPress theme, it is frequently used on public-facing websites. If your instance is reachable over the internet, it is considered more likely to be exposed to external attackers who can interact with the theme's features remotely.

Do I need to check my systems for this theme immediately?

Yes, the first step is to perform an inventory of your environment to identify any servers running Anesta version 1.5.3 or earlier. Once you locate the affected instances, assess their accessibility and the sensitivity of the data they handle to determine the urgency of applying available updates or security configurations.

References

patchstack.com/database/wordpress/theme/anesta/vulnerability/wordpre…

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.