External risk intelligence

RT-Theme 18 Extensions Object Injection Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-57744

The vulnerability affects a WordPress plugin, which is typically deployed as part of an internet-facing web application. Since web plugins are designed to process requests from the public internet in standard WordPress deployments, this creates a likely surface for network-based interaction.

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

A critical vulnerability has been identified in RT-Theme 18 Extensions, a component used within WordPress websites, that could allow attackers to inject malicious code. This "Object Injection" flaw, stemming from the deserialization of untrusted data, poses a significant risk due to its potential for widespread exploitation across the internet.

Untrusted data can be injected into systems.
It allows code execution on affected websites.
Confirm relevance and potential exposure of this plugin.

Attack Path

How an attacker could exploit the issue

An attacker can exploit this vulnerability by sending specially crafted data over the network to a vulnerable website running the RT-Theme 18 | Extensions plugin. This data can trigger the deserialization of untrusted input within the plugin, leading to the injection of malicious objects. When successful, this can allow an attacker to execute arbitrary code on the server, compromise data integrity, and disrupt service availability.

No authentication or user interaction needed.
Plugin processes untrusted, serialized data.
Full server compromise and data manipulation.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an attacker to inject malicious objects into the system when the affected component processes untrusted data. This could potentially lead to unauthorized modification or execution of code, impacting the integrity and availability of the service.

System integrity and availability could be affected.
Remote code execution via deserialization.
Service disruption or compromise.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in RT-Theme 18 | Extensions requires immediate attention from the application owners and platform teams responsible for managing WordPress instances. The first practical step is to identify all deployments of the affected plugin, confirm its exposure to the internet, and determine business criticality. Once accountable owners are identified, a risk-based remediation plan can be developed, which may involve coordinating with vendors or applying vendor-supplied fixes.

Application owners should own the issue.
Verify plugin reachability and business criticality.
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 RT-Theme 18 Extensions?

RT-Theme 18 Extensions is a WordPress plugin component designed to add features and functionality to the RT-Theme 18 WordPress theme. It is commonly installed alongside this theme to manage site elements and expand the core capabilities of the web application's design framework.

What does deserialization of untrusted data mean for CVE-2026-57744?

This vulnerability, classified as CWE-502, occurs when the plugin takes data from an outside source and converts it back into an object without checking if it is safe. Because the plugin blindly trusts this input, an attacker can supply a specially crafted object that forces the server to execute unintended, malicious commands.

How is this object injection vulnerability triggered?

The flaw is triggered when the plugin processes malicious, serialized data sent over the network. It does not require an attacker to have a user account or for a legitimate user to click on anything. Simply sending the malformed data to the application is enough to potentially initiate the attack, provided the site is running an affected version.

Do I need to worry if my site uses this plugin?

You should prioritize this if your site is reachable from the internet. Halo Surface Signal identifies this as a likely risk because WordPress plugins are inherently built to handle public web traffic. If your instance is internet-facing, it is exposed to these network-based requests by default, which increases the likelihood of an attacker successfully targeting the plugin.

What should I do first to address this vulnerability?

Start by performing an inventory to locate every instance of this plugin running in your environment. Once you have identified where it is deployed, assess whether those specific sites are internet-facing and how critical they are to your business operations. Use this information to coordinate with your technical team to plan for vendor updates or to restrict access to the affected components.

References

patchstack.com/database/Wordpress/Plugin/rt18-extensions/vulnerabili…

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.