External risk intelligence

Unauthenticated PHP Object Injection in Contact Form 7 and Constant Contact Integration

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-49106

An unauthenticated PHP Object Injection vulnerability exists in the Integration for Contact Form 7 and Constant Contact plugin. Attackers could exploit this to execute arbitrary code on the server, potentially compromising the website and its data. Confirming if this plugin is in use and accessible from the internet is

4Halo Surface Signal

Deserialization

External exposure likelihood

Halo Surface Signal score for CVE-2026-49106

The vulnerability affects a WordPress plugin designed for contact forms, which are inherently intended to be public-facing web components. As a web-based integration plugin, it is commonly deployed on public-facing websites to handle user input, making the attack surface frequently reachable from the internet.

PCI scan relevance

PCI Relevance for CVE-2026-49106

Yes

CVE-2026-49106 — Halo PCI Relevance: Yes. Under typical PCI ASV external scan criteria, this issue may be flagged for scan prioritization.

This vulnerability is a PHP Object Injection that can lead to remote code execution, which is a critical finding for PCI scans.

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 WordPress plugin that integrates Contact Form 7 with Constant Contact. This issue, if exploited, could allow an unauthenticated attacker to inject and execute malicious code, potentially leading to significant compromise of affected systems. The main concern is confirming relevance and exposure to this type of integration.

  • An attacker can inject malicious code remotely.
  • Protects against broad, unauthenticated system compromise.
  • Confirm if this integration is in use.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by sending a specially crafted request to a website using the Integration for Contact Form 7 and Constant Contact plugin. Because the vulnerability is unauthenticated and exposed to the network, an attacker does not need any special access to the website. This could lead to the execution of arbitrary code on the server.

  • No authentication required.
  • Involves deserializing untrusted data.
  • Allows arbitrary code execution.

Live Threat

Current exploitation, exposure, and threat context

When supported by the advisory, an unauthenticated PHP Object Injection in the Integration for Contact Form 7 and Constant Contact plugin could allow an attacker to execute arbitrary code on the server. This could impact the integrity and availability of the affected WordPress site.

  • Server-side code execution.
  • Exploiting unauthenticated object injection.
  • Compromise of the website and its data.

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

This unauthenticated PHP Object Injection vulnerability in the Integration for Contact Form 7 and Constant Contact plugin requires immediate attention from teams managing WordPress sites. The first practical step is to identify all instances of this plugin across your web presence, confirm their accessibility from the internet, and then determine the business criticality of each affected site to prioritize remediation efforts. Coordination with vendor management or the plugin's support channels may be necessary if direct fixes are not readily available.

  • Plugin owners should verify exposure.
  • Confirm plugin reachability and business impact.
  • Plan remediation based on verified risk.

Frequently asked questions

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

It is a WordPress plugin that bridges Contact Form 7, a popular form-building tool, with Constant Contact, an email marketing service. Websites use this integration to automatically sync visitor information collected via contact forms directly into their marketing contact lists, streamlining lead generation and communication efforts.

What does PHP Object Injection mean for CVE-2026-49106?

This vulnerability is classified as CWE-502, Deserialization of Untrusted Data. In simple terms, the plugin incorrectly processes complex data structures sent by users. An attacker can supply a specially crafted object that the application reconstructs and executes, effectively tricking the server into running unintended, potentially harmful code.

How does an attacker trigger this vulnerability?

An attacker triggers this by sending a malicious request directly to the website. Because the vulnerability does not require a user to log in or hold special privileges, anyone with network access to the site can attempt this. Normal, legitimate use of a contact form—such as a visitor simply submitting their name and email—does not trigger the flaw; the request must be intentionally malformed to exploit the deserialization process.

Is my website at risk from this CVE?

If you are running an affected version of this plugin, your site is likely reachable from the internet. According to Halo Surface Signal, because this plugin is designed for public-facing contact forms, it is frequently accessible to remote attackers. You should consider the plugin a point of potential entry if your site allows public interaction through these integrated forms.

What should I do if I use this plugin?

Start by auditing your WordPress environments to identify all active installations of this specific plugin. Once you have a list, assess which sites are reachable from the internet and prioritize them. Since this is a server-level concern, check for official plugin updates or security patches from the vendor, and consult their support channels if you need guidance on removing or disabling the integration while a permanent solution is being deployed.

References

Sources and related resources

Primary sources: NVD, CVE.org.

NVDPublished