External risk intelligence

Photolia Theme Unauthenticated PHP Object Injection

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-78535

The vulnerability affects a WordPress theme, which is a component of a web application. WordPress sites are typically deployed as internet-facing web applications, making the attack surface commonly exposed to the public internet in standard deployment patterns.

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 addresses a critical unauthenticated PHP Object Injection vulnerability found in the Photolia software. The issue allows for significant compromise through network access without requiring user credentials, potentially impacting confidentiality, integrity, and availability of systems where Photolia is deployed. The primary concern is to confirm if your organization uses this specific software and assess any potential exposure.

Unauthenticated code injection in Photolia.
Critical flaw with broad network access.
Confirm relevance and assess exposure.

Attack Path

How an attacker could exploit the issue

An attacker can exploit this vulnerability without any authentication by sending specially crafted data to a vulnerable PHP application. This can lead to the injection and execution of arbitrary PHP code, potentially allowing the attacker to take full control of the affected system.

No authentication required.
Sends malicious serialized data.
Full system compromise possible.

Live Threat

Current exploitation, exposure, and threat context

An unauthenticated PHP object injection vulnerability in Photolia could allow an attacker to execute arbitrary code or access sensitive system information when certain conditions are met, potentially leading to a compromise of the application.

System configuration data.
Via unauthenticated remote request.
Potential for unauthorized code execution.

Operational Fix

Recommended remediation, mitigation, and detection steps

The unauthenticated PHP Object Injection vulnerability in Photolia themes requires immediate attention from the platform or web application owners. The first practical step is to inventory all instances of Photolia themes, determine their exposure and business criticality, and identify the specific accountable owner for each instance before planning remediation.

Platform or application owners should manage this.
Verify Photolia theme exposure and criticality.
Plan targeted remediation and 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 Photolia software?

Photolia is a WordPress theme designed for building and styling web-based galleries or portfolios. It functions as a functional layer within a WordPress environment, defining how site content is presented to visitors. Because it runs as part of the WordPress framework, it processes incoming web requests and data, making it a potential entry point for security vulnerabilities.

What does PHP Object Injection mean for CVE-2026-78535?

This vulnerability, classified as CWE-502, occurs when an application unsafely processes serialized PHP objects provided by a user. Instead of treating the data as simple text, the application inadvertently creates objects that can change the software's behavior. In the context of this CVE, it allows an attacker to manipulate these objects to execute unintended code or bypass security controls.

How does an attacker trigger this vulnerability?

An attacker triggers this issue by sending a specially crafted request containing malicious serialized data directly to the Photolia theme. Because the flaw is unauthenticated, the attacker does not need an account or administrative access to the site. Importantly, simply visiting the site or viewing public pages normally will not trigger the bug; the request must be specifically designed to exploit the deserialization process.

Is my site at risk if it uses Photolia?

According to Halo Surface Signal, Photolia is a WordPress theme, which are typically deployed as internet-facing web applications. This means the attack surface is often exposed to the public internet by default. If your instance is accessible via a web browser from the internet, it falls into the category of potential exposure for this vulnerability.

What steps should I take if I use Photolia?

Start by performing an inventory to locate every instance of the Photolia theme across your infrastructure. Determine which of these sites are internet-facing and assess the criticality of the data they handle. Once identified, assign an owner to each instance to manage the transition to a patched version or to consider alternative themes while working with the vendor for updates.

References

patchstack.com/database/wordpress/theme/photolia/vulnerability/wordp…

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.