External risk intelligence

PHP Object Injection in ActiveCampaign and Contact Form 7 Integration Plugin

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-9691

A critical unauthenticated PHP Object Injection vulnerability exists in an integration plugin for popular WordPress form builders. This flaw could allow attackers to execute arbitrary code on the server, potentially compromising website integrity and data. The risk is present if the integration is exposed to the intern

4Halo Surface Signal

Deserialization

External exposure likelihood

Halo Surface Signal score for CVE-2026-9691

This vulnerability exists in a WordPress plugin used for contact forms and integrations. Such plugins are typically installed on public-facing websites to process user submissions, making the vulnerable code path reachable via the internet as part of standard web application operations.

PCI scan relevance

PCI Relevance for CVE-2026-9691

Yes

CVE-2026-9691 — Halo PCI Relevance: Yes. Under typical PCI ASV external scan criteria, this issue may be flagged for scan prioritization.

This unauthenticated PHP object injection vulnerability in ActiveCampaign and Contact Form 7 integrations could lead to a PCI scan failure due to the potential for remote code execution.

Scan-prioritization guidance only—not a PCI DSS certification or ASV attestation.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Horizon Alert

Summary of the vulnerability and why it matters

A critical vulnerability has been identified in a widely used WordPress plugin that handles contact forms and integrations. This issue, classified as unauthenticated PHP Object Injection, could allow unauthorized access and manipulation of systems without requiring any credentials. The main concern is to confirm if our business utilizes this specific plugin and, if so, to what extent.

  • Unauthenticated code injection in website form plugins.
  • Critical flaw, affects integration and data handling.
  • Confirm relevance and understand potential exposure.

Attack Path

How an attacker could exploit the issue

An attacker can exploit this vulnerability by sending specially crafted data over the internet to a website using the affected integration plugin. This can lead to the injection of malicious code, potentially allowing the attacker to take full control of the website.

  • No authentication required.
  • Triggered by submitting crafted data.
  • Risk of complete website compromise.

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, potentially impacting the integrity and availability of the affected WordPress integration. The risk is present when the integration is exposed to the internet and handles serialized data in a way that allows for object injection.

  • Server-side code execution.
  • Unserialized data from untrusted sources.
  • Compromised website and data integrity.

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

This unauthenticated PHP object injection vulnerability impacts integration plugins used with popular WordPress form builders. Responsibility likely falls to the website's platform or application owner, in coordination with the security team. The first practical move is to identify all instances of the affected plugin, confirm their reachability and business criticality, and then prioritize remediation based on risk and operational impact.

  • Website platform and application owners.
  • Verify plugin reachability and criticality.
  • Plan remediation based on risk.

Frequently asked questions

What is the Integration for ActiveCampaign and Contact Form 7 plugin?

It is a WordPress plugin designed to bridge websites with marketing services. It connects form builders like Contact Form 7, WPForms, Elementor, and Ninja Forms to ActiveCampaign, allowing site owners to automatically sync data from user-submitted forms directly into their marketing automation workflows.

What does PHP Object Injection mean for CVE-2026-9691?

This vulnerability, classified as CWE-502, occurs when an application improperly handles serialized data. Because the plugin processes input without sufficient verification, an attacker can supply malicious objects that the server then processes. This essentially tricks the application into executing unintended instructions, potentially leading to unauthorized control over the website's operations.

How is this vulnerability triggered by an attacker?

An attacker triggers this flaw by sending specially crafted, malicious data to the website through the plugin. Crucially, this does not require the attacker to have an account or login credentials. The bug is only triggered when the plugin processes this untrusted input; it is not triggered by standard, legitimate interactions that do not contain the manipulated data objects.

Do I need to worry about this if my site is not public?

According to Halo Surface Signal, this vulnerability is particularly relevant to plugins installed on public-facing websites, as the vulnerable code path is reachable via the internet during normal form processing. If your installation is strictly internal and not accessible to the public internet, the practical risk of external, unauthenticated exploitation is significantly reduced.

What is the first step to address CVE-2026-9691?

Start by auditing your WordPress environments to identify if versions 1.1.1 or earlier of this specific integration plugin are installed. Once identified, evaluate the plugin's business necessity and its reachability. Prioritize disabling or isolating affected instances while awaiting formal patches from the developer to mitigate the risk of unauthorized system access.

References

Sources and related resources

Primary sources: NVD, CVE.org.

NVDPublished