External risk intelligence

PHP Object Injection in Happyforms Plugin

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-49768

An unauthenticated PHP object injection vulnerability exists in the Happyforms plugin, allowing attackers to potentially execute arbitrary PHP code. This could lead to unauthorized access and manipulation of data on affected websites. Readers should verify the presence and public accessibility of the Happyforms plugin

4Halo Surface Signal

Deserialization

External exposure likelihood

Halo Surface Signal score for CVE-2026-49768

Happyforms is a WordPress plugin used to create public-facing web forms. These forms are designed to be embedded on websites, making the associated processing endpoints commonly accessible to the public internet for form submission and data handling.

PCI scan relevance

PCI Relevance for CVE-2026-49768

Yes

CVE-2026-49768 — Halo PCI Relevance: Yes. Under typical PCI ASV external scan criteria, this issue may be flagged for scan prioritization.

This vulnerability involves unauthenticated PHP object injection, which could allow attackers to execute arbitrary code. Such vulnerabilities are considered high risk and are relevant to PCI scan requirements due to their potential to compromise systems handling sensitive data.

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

This advisory details a critical vulnerability in the Happyforms plugin, specifically an unauthenticated PHP object injection. This type of issue can allow unauthorized access and manipulation of data within affected systems. While the plugin is widely used for creating web forms, confirming its presence and potential exposure is the primary concern for leadership at this time.

  • Unauthenticated code injection in web forms.
  • Affects plugins on public-facing websites.
  • Verify relevance and potential exposure.

Attack Path

How an attacker could exploit the issue

An unauthenticated attacker could exploit this vulnerability by sending specially crafted data to a web form processed by the Happyforms plugin. This could lead to the injection of malicious PHP objects, potentially allowing the attacker to take control of the affected website.

  • No authentication required.
  • Triggered by submitting a web form.
  • Risk of full website compromise.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could impact WordPress sites using Happyforms by allowing unauthenticated attackers to inject and execute arbitrary PHP code. This could lead to the compromise of sensitive data, modification of site content, or disruption of service when the plugin is used in environments where it processes user-supplied input in an unsafe manner.

  • Website data and functionality at risk.
  • Code injection via unauthenticated requests.
  • Complete site compromise possible.

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability impacts Happyforms, a WordPress plugin frequently used for public-facing web forms. The primary responsibility for addressing this issue likely falls to the application owner or the team managing the WordPress site, in coordination with the security team for exposure assessment. The first practical step involves identifying all instances of Happyforms, verifying their accessibility from the internet, and confirming business criticality. Subsequent actions will depend on this assessment, potentially involving vendor coordination for a fix, or implementing temporary risk reduction measures if immediate patching is not feasible.

  • Application owners should address this.
  • Verify public exposure and criticality first.
  • Plan remediation based on verified risk.

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 Happyforms plugin?

Happyforms is a WordPress plugin used to build and manage web forms. It allows site owners to create contact forms, feedback surveys, or lead generation tools that visitors interact with directly on a website.

What does PHP Object Injection mean for CVE-2026-49768?

This vulnerability is classified as CWE-502, Deserialization of Untrusted Data. It means the plugin improperly processes serialized data provided by users. An attacker can supply a malicious PHP object that the application then inadvertently processes, potentially leading to unauthorized code execution or system compromise.

How is this vulnerability triggered?

An attacker triggers the bug by sending specially crafted input through a web form managed by the plugin. Because this does not require any user account or password, the action occurs without authentication. Simply visiting the site or browsing static pages will not trigger the vulnerability; it requires interacting with the specific form processing endpoints.

Is my website at risk from this CVE?

If you use an affected version of Happyforms, your risk depends on how the site is deployed. According to Halo Surface Signal, Happyforms is typically used for public-facing web forms, which often places the affected processing endpoints directly on the internet. Any instance reachable by the public is a primary concern for potential exploitation.

What steps should I take to respond?

Start by identifying all WordPress sites in your environment running Happyforms. Confirm which of these are accessible from the internet and evaluate their business criticality. Once your inventory is clear, prioritize monitoring for suspicious activity and consult the plugin developer for available updates or guidance on securing the form processing functions.

References

Sources and related resources

Primary sources: NVD, CVE.org.

NVDPublished