CVE-2026-13693: Bit Form WordPress Path Traversal Flaw

CVE-2026-13693 Overview

CVE-2026-13693 is a path traversal vulnerability in the Bit Form WordPress plugin versions prior to 3.1.0. The plugin fails to restrict form file-field values to a safe path before reading files and attaching them to notification emails. Unauthenticated attackers can abuse this behavior to read arbitrary files from the server, including the WordPress wp-config.php configuration file. The flaw is classified under [CWE-22] Improper Limitation of a Pathname to a Restricted Directory. Exposure of wp-config.php typically leaks database credentials, authentication salts, and secret keys.

Critical Impact
Unauthenticated remote attackers can exfiltrate sensitive files such as wp-config.php, exposing database credentials and secret keys used to sign WordPress authentication cookies.

Affected Products

Bit Form WordPress plugin versions before 3.1.0
WordPress sites with the vulnerable plugin activated
Any web server hosting the plugin, subject to file system read permissions of the PHP process

Discovery Timeline

2026-07-21 - CVE-2026-13693 published to NVD
2026-07-21 - Last updated in NVD database

Technical Details for CVE-2026-13693

Vulnerability Analysis

The Bit Form plugin processes submitted forms and, when configured, attaches uploaded file-field values to email notifications. The plugin trusts the file path supplied through the form submission without validating or normalizing it. An attacker can substitute the expected upload identifier with a relative or absolute path pointing to an arbitrary file on the server. When the plugin builds the notification email, it opens the attacker-controlled path and attaches the file contents. The recipient inbox, which may itself be attacker-controlled through form configuration or open notification routing, then receives the sensitive file. This turns a legitimate email-attachment feature into an arbitrary file read primitive that requires no authentication.

Root Cause

The root cause is missing input validation on the file-field value used as an email attachment source. The plugin does not enforce that the referenced file resides within the intended uploads directory. There is no canonicalization to resolve ../ sequences and no allow-list check against a trusted base path. This is a textbook [CWE-22] path traversal issue.

Attack Vector

Exploitation occurs over the network through the plugin's public form submission endpoint. No authentication or user interaction is required. An attacker crafts a form submission that sets the file-field value to a traversal path such as one resolving to wp-config.php or other server files readable by the PHP process. The plugin then reads the file and delivers it as an email attachment. Refer to the WPScan Vulnerability Report for technical details.

Detection Methods for CVE-2026-13693

Indicators of Compromise

Form submissions to Bit Form endpoints containing path traversal sequences such as ../, absolute paths, or references to wp-config.php
Outbound email traffic from the WordPress host with attachments matching sensitive file names or sizes inconsistent with legitimate form uploads
Web server access logs showing repeated POST requests to Bit Form submission handlers from a single source
SMTP relay logs delivering messages to unusual or external recipient addresses shortly after form submissions

Detection Strategies

Inspect PHP and web server logs for form submissions where file-field parameters contain non-upload filesystem paths
Alert on any Bit Form notification email whose attachment name resolves outside the WordPress uploads directory
Correlate form submission events with subsequent reads of wp-config.php or other sensitive files by the web server user

Monitoring Recommendations

Enable file integrity monitoring on wp-config.php and other sensitive WordPress files to flag unexpected access
Log outbound SMTP traffic and review recipient domains for notification emails generated by the plugin
Review WordPress admin audit trails to confirm the plugin version and identify recent form configuration changes

How to Mitigate CVE-2026-13693

Immediate Actions Required

Update the Bit Form plugin to version 3.1.0 or later on all WordPress installations
Rotate WordPress database credentials, authentication keys, and salts in wp-config.php if exposure is suspected
Audit recent form submissions and notification emails for evidence of arbitrary file read attempts

Patch Information

The vendor addressed the issue in Bit Form version 3.1.0 by restricting file-field values used for email attachments to safe paths. Administrators should apply the update through the WordPress plugin dashboard or WP-CLI. See the WPScan Vulnerability Report for advisory details.

Workarounds

Deactivate and remove the Bit Form plugin until it can be updated to 3.1.0 or later
Disable email notifications containing file attachments in Bit Form configuration
Restrict access to Bit Form submission endpoints with a web application firewall rule blocking path traversal patterns in form parameters
Enforce least-privilege filesystem permissions so the PHP process cannot read files outside the WordPress document root

bash

# Configuration example: update the plugin via WP-CLI
wp plugin update bit-form --version=3.1.0

# Verify installed version
wp plugin get bit-form --field=version