Overview

The Eventin – Event Calendar, Event Registration, Tickets & Booking (AI Powered) plugin for WordPress, developed by arraytics, is used for event management on WordPress sites. The plugin is vulnerable to Local File Inclusion (LFI), which allows attackers to include files on a server through a web browser. This vulnerability exists in all versions up to and including 4.1.22 and is tracked under CVE-2026-15667 with a CVSS score of 7.5.

Understanding the Vulnerability / Threat

Root Cause Analysis

The root cause of this vulnerability is the lack of proper validation and sanitization of the 'event_layout' parameter. This parameter is used to specify the layout for events, but due to inadequate checks, an attacker can manipulate this parameter to include arbitrary PHP files from the server. This flaw falls under the CWE-98 category, which pertains to Improper Control of Filename for Inclusion.

Attack Surface & Vector

The attack surface for this vulnerability involves the 'event_layout' parameter, which can be manipulated by authenticated attackers with contributor-level access and above. The attack vector is network-adjacent, as the attacker needs to have access to the WordPress site's REST API to set the malicious 'event_layout' value. The etn_manage_event capability, which is assigned to Contributors by default, allows any Contributor-level user to exploit this vulnerability without additional configuration.

Exploitation Mechanics — Scenario Walkthrough

Scenario: Compromising a Corporate WordPress Site Using CVE-2026-15667

1. Initial Position: An attacker gains contributor-level access to a WordPress site using the Eventin plugin.
2. Triggering the Flaw: The attacker crafts a malicious request to the REST API, specifically targeting the 'event_layout' parameter with a path to an arbitrary PHP file on the server, such as ../../../../wp-config.php. This file inclusion is possible because the plugin fails to properly validate and sanitize the input.
3. What Breaks: The security boundary that fails is the plugin's file inclusion validation. By including arbitrary PHP files, the attacker can execute any PHP code within those files. This leads to a chain reaction where the attacker can bypass access controls, obtain sensitive data, or achieve code execution.
4. Attacker's Prize: With the ability to execute arbitrary PHP code, the attacker can escalate their privileges, access sensitive information, or take control of the site. They may use this access to further exploit the site, such as deploying malware, creating backdoors, or exfiltrating data.

Real-World Impact

The impact of this vulnerability can be significant. An attacker can use it to:
- Bypass access controls and gain unauthorized access to sensitive areas of the site.
- Obtain sensitive data, such as database credentials or user information.
- Achieve code execution, potentially leading to full site compromise or deployment of malware.
- Escalate privileges to gain administrative access to the site.

While there is no confirmation of active exploitation in the wild, the CVSS score of 7.5 indicates a high severity vulnerability that should be addressed promptly.

Detection & Defense

Immediate Mitigations

- Upgrade the Eventin plugin to version 4.1.23 or later.
- Limit contributor-level access and monitor user activity closely.
- Implement a Web Application Firewall (WAF) to detect and block suspicious requests.

Detection Strategies

- Monitor REST API requests for unusual patterns, especially those targeting the 'event_layout' parameter.
- Implement SIEM rules to detect and alert on potential file inclusion attempts.
- Regularly review user activity and access logs for signs of exploitation.

Long-Term Hardening

- Enforce strict access controls and limit user privileges based on roles.
- Implement a defense-in-depth strategy with multiple layers of security, including firewalls, intrusion detection systems, and regular security audits.
- Keep all plugins and themes up-to-date to prevent exploitation of known vulnerabilities.

Key Takeaways

  • The Eventin plugin for WordPress is vulnerable to Local File Inclusion (LFI) due to improper validation of the 'event_layout' parameter.
  • Authenticated attackers with contributor-level access can exploit this vulnerability to include and execute arbitrary PHP files on the server.
  • Immediate mitigation involves upgrading to version 4.1.23 or later and closely monitoring user activity.
  • Detection strategies include monitoring REST API requests and implementing SIEM rules.
  • Long-term hardening involves enforcing strict access controls, implementing defense-in-depth, and keeping software up-to-date.

Sources

  • National Vulnerability Database (NVD) - CVE-2026-15667