External risk intelligence

Gunslinger Theme Unauthenticated PHP Object Injection

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-62018

The vulnerability exists in a WordPress theme. WordPress themes are public-facing web components by design, intended to render content to the internet. Because the vulnerable code is part of the site's web-facing interface, it is commonly exposed to public network requests.

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 vulnerability in the Gunslinger theme, which could allow unauthenticated attackers to inject malicious code into affected systems. The primary concern is confirming if your organization utilizes this specific theme and assessing potential exposure.

Unauthenticated code injection flaw exists.
Confirms relevance and potential exposure.
Verify theme usage and assess risk.

Attack Path

How an attacker could exploit the issue

An attacker could potentially exploit this vulnerability by sending a specially crafted request over the network. This request would target an unauthenticated feature within the Gunslinger theme, leading to the injection of malicious PHP objects. If successful, this could allow an attacker to compromise the integrity of the application.

Unauthenticated network access required.
Triggered by sending malicious PHP objects.
Risk of full application compromise.

Live Threat

Current exploitation, exposure, and threat context

An unauthenticated PHP Object Injection vulnerability in the Gunslinger theme could allow an attacker to remotely execute arbitrary code on the server, potentially leading to a full system compromise when the application processes unsanitized user input. This could affect the integrity and availability of the web service and any data it manages.

Server-side code execution.
Unsanitized input processing.
Complete server compromise.

Operational Fix

Recommended remediation, mitigation, and detection steps

This unauthenticated PHP object injection vulnerability in the Gunslinger theme is likely exposed externally, making it critical to address. Infrastructure or platform teams managing the WordPress environment should lead the response by first identifying all instances of the affected theme, confirming their reachability and business criticality. Once confirmed, a risk-based remediation plan should be developed in coordination with the accountable application or site owner.

Application owners should investigate and track.
Verify theme deployment and external reachability.
Plan remediation with vendor coordination.

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 Gunslinger theme?

Gunslinger is a WordPress theme, which acts as a foundational template for managing the visual layout and user interface of a website. Themes like this handle how content is rendered to visitors, often integrating server-side functions to manage site display and features. Because it is part of the WordPress ecosystem, it runs within the web server environment, directly interacting with incoming HTTP requests.

What does PHP Object Injection mean for CVE-2026-62018?

This vulnerability is classified as CWE-502, which occurs when an application deserializes untrusted data without proper validation. In the context of CVE-2026-62018, the Gunslinger theme improperly handles input, allowing an attacker to inject malicious PHP objects. When the server processes these objects, it can be forced to execute unintended code, potentially granting the attacker control over the application's logic and data.

How does an attacker trigger this vulnerability?

An attacker triggers this flaw by sending a specially crafted, malicious request over the network to the affected WordPress site. The vulnerability relies on the theme's feature for processing user input without adequate sanitation. Simply visiting the site or viewing pages does not trigger the bug; the attacker must specifically target the vulnerable, unauthenticated feature within the theme's codebase to initiate the malicious injection.

Why is this CVE considered relevant for my web server?

According to Halo Surface Signal, this vulnerability is highly relevant because it affects a WordPress theme, which is inherently designed to be a public-facing component. Since the theme processes requests from the internet to render site content, it resides on the attack surface. Any system running the affected version of Gunslinger is likely exposed to external network traffic, making it a potential target for remote, unauthenticated actors.

Do I need to take action if I use the Gunslinger theme?

Yes, you should prioritize investigating your environment to locate all instances of the Gunslinger theme. First, confirm if your sites are running version 1.11 or older. Work with your site owners to assess the business impact of these installations and prepare a remediation plan. Since this is an external-facing issue, coordinating with your application team to manage and update these components is the essential first step toward securing your web infrastructure.

References

patchstack.com/database/wordpress/theme/gunslinger/vulnerability/wor…

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.