CVE-2024-9267 Overview
CVE-2024-9267 is a Reflected Cross-Site Scripting (XSS) vulnerability affecting the Easy WordPress Subscribe – Optin Hound plugin for WordPress. The flaw stems from the use of add_query_arg without appropriate URL escaping in all versions up to and including 1.4.3. Unauthenticated attackers can inject arbitrary web scripts into pages, which execute when a victim clicks a crafted link. The vulnerability is classified as [CWE-79] Improper Neutralization of Input During Web Page Generation.
Critical Impact
An unauthenticated attacker can execute arbitrary JavaScript in a victim's browser session by tricking the user into clicking a malicious link, potentially leading to session hijacking, credential theft, or administrative account takeover.
Affected Products
- Easy WordPress Subscribe – Optin Hound plugin (all versions up to and including 1.4.3)
- WordPress installations running the vulnerable plugin
- Administrative interfaces exposed by the plugin's subscribers submenu page
Discovery Timeline
- 2024-10-01 - CVE-2024-9267 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2024-9267
Vulnerability Analysis
The vulnerability resides in the plugin's subscribers view file at includes/subscribers/views/view-submenu-page-subscribers.php. The code invokes WordPress's add_query_arg function with user-controllable input and reflects the resulting URL back into the rendered page without proper escaping. Because add_query_arg returns URLs that include the current request's query string by default, attackers can inject malicious parameters that end up in the HTML response unsanitized.
This pattern is a well-documented class of reflected XSS affecting many WordPress plugins. Exploitation requires user interaction, typically clicking a crafted link, and the payload executes in the browser context of the victim visiting the affected WordPress admin page.
Root Cause
The root cause is missing output escaping around the return value of add_query_arg. WordPress documentation explicitly warns developers to pass the result through esc_url or esc_url_raw before echoing it into HTML. The vulnerable plugin omits this escaping step, allowing attacker-controlled query string content to break out of the URL context and inject arbitrary HTML or JavaScript.
Attack Vector
An attacker crafts a URL to the vulnerable subscribers submenu page with a malicious query string containing JavaScript payloads. The attacker delivers this link via phishing email, social media, or a compromised website. When an authenticated WordPress administrator or user with plugin access clicks the link, the injected script executes in their browser under the WordPress site's origin. Consequences include session cookie theft, forced administrative actions via CSRF, and injection of persistent backdoors.
Technical details are available in the Wordfence Vulnerability Report and the WordPress Opt-In Hound Code.
Detection Methods for CVE-2024-9267
Indicators of Compromise
- HTTP requests to WordPress admin pages containing suspicious query string parameters with encoded <script>, javascript:, or onerror= payloads
- Web server access logs showing unusual referrers pointing to the Opt-In Hound subscribers submenu URL
- Unexpected administrator account creations or plugin/theme modifications following admin sessions that visited crafted links
Detection Strategies
- Deploy web application firewall rules that identify reflected XSS patterns targeting the wp-admin endpoints exposed by the Opt-In Hound plugin
- Monitor for outbound requests from administrator browsers to unfamiliar domains, which may indicate exfiltration by injected JavaScript
- Inspect WordPress activity logs for anomalous privilege changes, user creations, or option modifications following admin logins
Monitoring Recommendations
- Enable verbose logging on the WordPress site and forward logs to a centralized SIEM for query string analysis
- Alert on any HTTP 200 response to the vulnerable submenu page that includes reflected script-like content in the response body
- Track plugin inventory across managed WordPress sites to identify hosts running Opt-In Hound version 1.4.3 or earlier
How to Mitigate CVE-2024-9267
Immediate Actions Required
- Identify all WordPress installations running the Easy WordPress Subscribe – Optin Hound plugin and confirm the installed version
- Deactivate and remove the plugin on any site where a patched version is not yet available
- Instruct administrators to avoid clicking untrusted links while authenticated to the WordPress admin interface
Patch Information
As of the last NVD update, no fixed version beyond 1.4.3 is confirmed in the referenced advisories. Administrators should check the WordPress Plugin Developer Info page for the latest release status and apply any subsequent patched version as soon as it becomes available. Until a fix is published, uninstalling the plugin is the most reliable remediation.
Workarounds
- Restrict access to the WordPress admin panel using IP allowlists at the web server or firewall layer
- Deploy a WAF ruleset that blocks HTTP requests containing common XSS payload signatures targeting wp-admin paths
- Enforce Content Security Policy (CSP) headers that disallow inline script execution to reduce the impact of reflected XSS
- Require administrators to use dedicated, hardened browsers or sessions for WordPress management tasks
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
