External risk intelligence

PHP Object Injection in Quirky Theme Versions 1.23 and Earlier.

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-54857

The vulnerability affects a WordPress theme. WordPress themes are core components of web applications that are typically deployed as internet-facing websites or web applications, making the code paths within the theme commonly reachable via 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

A critical vulnerability has been identified in Quirky, a software component, that could allow unauthenticated attackers to inject malicious code. This type of vulnerability poses a significant risk because it can be exploited remotely, potentially leading to severe compromise of affected systems. The main concern is confirming if this software is in use and, if so, assessing the potential exposure.

Unauthenticated code injection risk.
Critical flaw impacts widely used software.
Confirm relevance and assess exposure.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by sending specially crafted data over the network to a web application using a vulnerable version of the Quirky theme. This could allow the attacker to inject and execute arbitrary PHP code on the server, potentially leading to a complete compromise of the application.

No authentication is required.
Triggered by network requests.
Enables remote code execution.

Live Threat

Current exploitation, exposure, and threat context

This unauthenticated PHP object injection vulnerability could allow an attacker to execute arbitrary code on the server when supported by the advisory's conditions. This could affect system data and service behavior.

System data and service behavior.
Via insecure deserialization when code is reachable.
Potential for unauthorized code execution.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in the Quirky theme requires immediate attention from the platform or application team responsible for managing WordPress sites. The first critical step is to inventory all deployments of the Quirky theme, determine their exposure and business criticality, and identify the accountable system owner. This information will inform a prioritized remediation plan, balancing risk reduction with operational constraints.

Platform/application teams own this issue.
Verify theme deployment and public exposure first.
Plan remediation or mitigation based on risk.

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.

Free EASM Trial See How Signal Works

Frequently asked questions

What is the Quirky software component?

Quirky is a WordPress theme used to manage the visual presentation and layout of websites built on the WordPress content management platform. Like many themes, it contains server-side PHP code that handles site functionality. This vulnerability affects version 1.23 and all earlier versions of this specific theme.

What does PHP object injection mean in CVE-2026-54857?

This is a weakness identified as CWE-502, occurring when an application insecurely processes user-supplied data during deserialization. In the context of this CVE, it means an attacker can send specially formatted data that the Quirky theme incorrectly treats as a trusted object. This allows the attacker to manipulate the data structures the application uses, which can lead to unauthorized execution of malicious code on the server.

How is this vulnerability triggered?

An attacker triggers this flaw by sending a crafted network request to the web application. Because the vulnerability does not require authentication, the attacker does not need a user account or special permissions to attempt the attack. It is important to note that this is not triggered by standard site traffic or normal administrative actions; it specifically requires the transmission of malicious, structured data payloads that the theme's code attempts to deserialize.

Why should I care about this CVE?

According to Halo Surface Signal, this vulnerability is significant because it affects a WordPress theme, which is a core component typically deployed on internet-facing websites. Because these websites are exposed to public network requests, the vulnerable code paths are commonly reachable by remote actors. If your organization uses this theme on public-facing infrastructure, the potential for unauthorized remote code execution makes this a high-priority concern.

Do I need to take action if I use Quirky?

Yes. Your first step is to identify every instance where the Quirky theme is currently installed within your environment. Once you have a complete inventory, verify if the installed version is 1.23 or older. After confirming the presence of the vulnerable software, work with your platform management team to assess the business risk and establish a timeline to apply security updates or remove the theme from your production systems.

References

patchstack.com/database/wordpress/theme/quirky/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.