CVE-2026-39711: RT-Theme 18 Information Disclosure Flaw

CVE-2026-39711 Overview

A Sensitive Data Exposure vulnerability has been identified in the RT-Theme 18 Extensions WordPress plugin (rt18-extensions) developed by stmcan. This vulnerability, classified under CWE-201 (Insertion of Sensitive Information Into Sent Data), allows attackers to retrieve embedded sensitive data from the affected plugin. The flaw exists in all versions through 2.5, potentially exposing confidential information to unauthorized parties.

Critical Impact

Attackers can extract sensitive data embedded within outgoing communications or responses from the RT-Theme 18 Extensions plugin, potentially compromising user credentials, configuration details, or other confidential information.

Affected Products

• RT-Theme 18 | Extensions (rt18-extensions) versions through 2.5
• WordPress installations utilizing the rt18-extensions plugin
• Websites running RT-Theme 18 with the associated extensions plugin

Discovery Timeline

• April 8, 2026 - CVE-2026-39711 published to NVD
• April 8, 2026 - Last updated in NVD database

Technical Details for CVE-2026-39711

Vulnerability Analysis

This vulnerability falls under the Sensitive Data Exposure category (CWE-201), which occurs when an application inadvertently includes sensitive information in data that is transmitted to unauthorized recipients. In the context of the RT-Theme 18 Extensions plugin, the vulnerability allows malicious actors to retrieve embedded sensitive data that should remain protected.

The flaw affects WordPress websites utilizing the rt18-extensions plugin, which is designed to extend the functionality of the RT-Theme 18 WordPress theme. When exploited, this vulnerability can lead to unauthorized access to sensitive information that the plugin processes or transmits.

Root Cause

The root cause of this vulnerability lies in the improper handling of sensitive data within the rt18-extensions plugin. The plugin fails to adequately filter or sanitize sensitive information before including it in data that is sent to users or external services. This design flaw results in the unintended exposure of confidential data that should be protected from unauthorized access.

Specifically, the vulnerability stems from insufficient data separation mechanisms that allow sensitive information to be embedded in responses or transmitted data without proper access controls or encryption.

Attack Vector

The attack vector for this vulnerability involves an attacker interacting with WordPress installations running the vulnerable rt18-extensions plugin. By crafting specific requests or accessing certain functionality within the plugin, an attacker can retrieve sensitive data that has been inadvertently embedded in the plugin's responses.

The exploitation does not require authentication in certain scenarios, allowing remote attackers to extract sensitive information. This could include configuration data, user information, or other confidential details processed by the plugin.

For detailed technical information about this vulnerability, refer to the Patchstack Vulnerability Report.

Detection Methods for CVE-2026-39711

Indicators of Compromise

• Unusual outbound data patterns from WordPress installations containing sensitive information
• Unexpected access to plugin endpoints that handle or return configuration data
• Log entries showing requests to rt18-extensions plugin files with abnormal parameters
• Evidence of data exfiltration attempts targeting WordPress plugin directories

Detection Strategies

• Monitor HTTP responses from the rt18-extensions plugin for inclusion of sensitive data patterns
• Implement web application firewall (WAF) rules to detect suspicious queries to rt18-extensions endpoints
• Review WordPress access logs for unusual request patterns targeting the plugin
• Utilize security scanning tools to identify vulnerable versions of rt18-extensions

Monitoring Recommendations

• Enable comprehensive logging for all WordPress plugin activity
• Configure alerts for data exposure patterns in outbound traffic from the WordPress installation
• Regularly audit the rt18-extensions plugin configuration and data handling processes
• Monitor for version-specific indicators of the vulnerable plugin in your WordPress deployments

How to Mitigate CVE-2026-39711

Immediate Actions Required

• Identify all WordPress installations running rt18-extensions version 2.5 or earlier
• Check for available updates to the rt18-extensions plugin through the WordPress plugin repository
• Temporarily disable the rt18-extensions plugin if a patch is not yet available
• Review access logs to determine if the vulnerability has been exploited

Patch Information

Organizations should monitor the official RT-Theme 18 Extensions plugin channels and the Patchstack vulnerability database for patch availability. Update to a patched version as soon as one becomes available from the vendor.

Workarounds

• Disable the rt18-extensions plugin until a security patch is released
• Implement WAF rules to restrict access to sensitive plugin endpoints
• Use WordPress security plugins to monitor and block suspicious data access attempts
• Limit plugin functionality to essential features while awaiting a permanent fix

# WordPress CLI command to check plugin version
wp plugin list --name=rt18-extensions --fields=name,version,status

# Disable plugin temporarily if vulnerable
wp plugin deactivate rt18-extensions

# Check for available updates
wp plugin update rt18-extensions --dry-run