CVE-2025-39483: Eventer Code Injection Vulnerability

CVE-2025-39483 Overview

CVE-2025-39483 is a code injection vulnerability in the imithemes Eventer plugin for WordPress. The flaw affects all versions of Eventer up to and including 3.9.9.1. Attackers can exploit the vulnerability over the network without authentication or user interaction. The root cause is improper control of code generation through shortcode processing [CWE-94].

Successful exploitation allows an attacker to inject and execute code within the WordPress site context. This can lead to limited disclosure of information and unauthorized modification of site data. The issue is documented in the Patchstack WordPress Plugin Advisory.

Critical Impact
Unauthenticated attackers can inject code through vulnerable shortcode handling in the Eventer plugin, compromising WordPress site confidentiality and integrity.

Affected Products

imithemes Eventer plugin for WordPress
All versions from initial release through 3.9.9.1
WordPress sites with Eventer installed and activated

Discovery Timeline

2025-08-14 - CVE-2025-39483 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-39483

Vulnerability Analysis

The vulnerability resides in the Eventer plugin's shortcode processing logic. The plugin fails to properly control code generation when evaluating shortcode attributes or content supplied by requests. An attacker can craft input that the plugin interprets as executable code rather than data.

The issue maps to [CWE-94] Improper Control of Generation of Code. Because the attack vector is network-based and no privileges or user interaction are required, remote attackers can target any WordPress instance running a vulnerable Eventer version. The impact is limited to partial confidentiality and integrity effects, with no availability impact recorded.

Root Cause

The plugin passes attacker-influenced values into a code generation or evaluation path without adequate sanitization. Shortcode handlers in WordPress plugins commonly invoke dynamic function calls or interpret user-controlled strings. When the Eventer plugin processes a malicious shortcode, injected payloads become part of the code executed by the PHP interpreter.

Attack Vector

An unauthenticated attacker submits crafted content that triggers the vulnerable shortcode path. This can occur through any input surface that renders shortcodes, including posts, pages, comments, or plugin-specific endpoints that reflect user-supplied attributes. The Patchstack advisory identifies this as a shortcode injection issue.

Exploitation does not require credentials or social engineering. Refer to the Patchstack advisory for further technical detail on the affected code path.

Detection Methods for CVE-2025-39483

Indicators of Compromise

Unexpected PHP files or modified theme/plugin files under wp-content/plugins/eventer/ or wp-content/uploads/
WordPress posts, pages, or comments containing Eventer shortcodes with unusual attributes or embedded PHP constructs
Outbound network connections from the web server to unknown hosts following shortcode rendering
New administrator accounts or modified user roles that cannot be attributed to legitimate activity

Detection Strategies

Inventory all WordPress instances and identify sites running the Eventer plugin at version 3.9.9.1 or earlier
Review web server access logs for requests containing Eventer shortcode names with suspicious attribute values
Scan the WordPress database for post content that includes Eventer shortcodes injected outside expected editorial workflows
Compare file hashes of plugin, theme, and core WordPress files against known-good baselines

Monitoring Recommendations

Enable PHP error and access logging on the web server and centralize logs for review
Alert on creation or modification of PHP files within the WordPress installation directory
Monitor for spawning of shell processes or outbound connections initiated by the web server user
Track WordPress administrative actions such as user creation, role changes, and plugin installations

How to Mitigate CVE-2025-39483

Immediate Actions Required

Identify all WordPress sites using the Eventer plugin and confirm the installed version
Deactivate the Eventer plugin on any site running version 3.9.9.1 or earlier until a fixed release is applied
Restrict shortcode rendering surfaces exposed to unauthenticated users where possible
Review recent posts, pages, and comments for evidence of malicious shortcode injection

Patch Information

Consult the Patchstack WordPress Plugin Advisory for the latest information on a fixed version. Update the Eventer plugin to a release later than 3.9.9.1 once the vendor publishes a patched version. Verify the update through the WordPress admin dashboard or by inspecting the plugin readme.txt header.

Workarounds

Remove or deactivate the Eventer plugin until a patched version is installed
Deploy a Web Application Firewall rule to block requests containing Eventer shortcode patterns with suspicious payloads
Restrict content creation privileges to trusted users and disable shortcode rendering in comments
Apply virtual patching through a WordPress security plugin that supports the Patchstack advisory feed

bash

# Configuration example: disable the Eventer plugin via WP-CLI
wp plugin deactivate eventer
wp plugin status eventer