CVE-2026-78275 Overview
CVE-2026-78275 is an arbitrary file deletion vulnerability affecting the Fluent Boards Pro WordPress plugin in versions up to and including 2.0.11. The flaw allows authenticated users with Editor-level privileges to delete arbitrary files on the underlying server through improper path handling. Successful exploitation can remove critical WordPress files such as wp-config.php, forcing the site into a setup state and enabling further compromise. The issue is categorized as a path traversal weakness [CWE-22].
Critical Impact
An authenticated Editor can delete arbitrary files on the WordPress host, causing site outage and enabling secondary attack chains including takeover through re-installation.
Affected Products
- Fluent Boards Pro WordPress plugin versions <= 2.0.11
- WordPress sites running the vulnerable plugin with Editor-role accounts
- Environments where the plugin's file-handling endpoints are reachable
Discovery Timeline
- 2026-08-27 - CVE-2026-78275 published to NVD
- 2026-08-27 - Last updated in NVD database
Technical Details for CVE-2026-78275
Vulnerability Analysis
The vulnerability resides in a file-handling routine within Fluent Boards Pro that fails to sanitize user-supplied path input. An authenticated user holding the Editor role can supply a crafted path that resolves outside the plugin's intended directory. The plugin then invokes a delete operation on the attacker-chosen file. Because the operation runs with the privileges of the web server, any file writable by that account can be removed.
Deleting wp-config.php triggers WordPress to re-enter the installation flow on the next request. An attacker who reaches this state before an administrator can point the site at a database they control and take over the installation. Other high-impact targets include .htaccess, plugin files, and theme configuration files.
Root Cause
The root cause is missing validation of a file path parameter passed to a delete function [CWE-22]. The plugin does not constrain the target to an allow-listed directory and does not canonicalize the path to reject traversal sequences such as ../. The authorization check only verifies that the caller is authenticated at Editor level, which is insufficient for an operation that touches the file system.
Attack Vector
Exploitation requires network access to the WordPress site and valid credentials for an account with Editor privileges. The attacker submits a request to the vulnerable plugin endpoint with a manipulated path parameter that references a file outside the intended scope. No user interaction from an administrator is required. Refer to the Patchstack Vulnerability Report for advisory details.
Detection Methods for CVE-2026-78275
Indicators of Compromise
- Unexpected deletion of wp-config.php, .htaccess, or plugin and theme files on WordPress hosts running Fluent Boards Pro.
- WordPress unexpectedly presenting the initial installation wizard on a previously configured site.
- HTTP requests to Fluent Boards Pro admin-ajax or REST endpoints containing traversal sequences such as ../ in file or path parameters.
Detection Strategies
- Inspect web server access logs for authenticated POST requests to Fluent Boards Pro endpoints referencing paths outside wp-content/plugins/fluent-boards-pro/.
- Deploy file integrity monitoring on the WordPress root, wp-content/, and configuration files to alert on unexpected deletions.
- Correlate Editor-role session activity with file system delete events occurring in close time proximity.
Monitoring Recommendations
- Enable audit logging for WordPress role activity, particularly Editor accounts interacting with plugin endpoints.
- Forward web server and WordPress audit logs to a centralized platform for retention and query.
- Alert on any web-server process performing unlink() operations outside of expected upload and cache directories.
How to Mitigate CVE-2026-78275
Immediate Actions Required
- Update Fluent Boards Pro to a version later than 2.0.11 as soon as a fixed release is available from the vendor.
- Audit all Editor-level accounts and remove or downgrade any that are unnecessary.
- Rotate credentials for Editor accounts and enforce multi-factor authentication on the WordPress admin interface.
Patch Information
Consult the Patchstack Vulnerability Report for the fixed version and vendor-supplied remediation guidance. Apply the update through the WordPress plugin management interface or via WP-CLI.
Workarounds
- Restrict access to the WordPress admin interface using IP allow-listing at the web server or WAF layer until a patch is applied.
- Deploy a web application firewall rule that blocks requests containing ../ sequences in parameters targeting Fluent Boards Pro endpoints.
- Set filesystem permissions so that the web server user cannot delete wp-config.php, .htaccess, and other critical files.
# Example: harden critical WordPress file permissions
chown root:www-data /var/www/html/wp-config.php
chmod 640 /var/www/html/wp-config.php
chattr +i /var/www/html/wp-config.php
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
