CVE-2026-57790: Billey Theme File Inclusion Vulnerability

CVE-2026-57790 Overview

CVE-2026-57790 is a PHP Local File Inclusion (LFI) vulnerability in the ThemeMove Billey WordPress theme. The flaw stems from improper control of a filename used in a PHP include or require statement, classified under [CWE-98]. Authenticated attackers can supply crafted input that causes the theme to include arbitrary local PHP files. Successful exploitation can lead to disclosure of sensitive files, execution of attacker-influenced PHP, and full site compromise. The issue affects all Billey theme versions up to and including 2.1.8.

Critical Impact
Attackers with low-privilege access can include arbitrary local PHP files, resulting in confidentiality, integrity, and availability loss across affected WordPress sites.

Affected Products

ThemeMove Billey WordPress Theme versions n/a through <= 2.1.8
WordPress installations using the Billey theme
Any site hosting the vulnerable theme package

Discovery Timeline

2026-07-13 - CVE-2026-57790 published to NVD
2026-07-13 - Last updated in NVD database

Technical Details for CVE-2026-57790

Vulnerability Analysis

The Billey theme passes user-controllable input into a PHP file inclusion statement without adequate validation. This is a classic PHP Remote File Inclusion weakness ([CWE-98]) that manifests locally because PHP's allow_url_include is typically disabled on hardened servers. Attackers who can reach the vulnerable endpoint influence the path argument used by include, include_once, require, or require_once. The PHP engine then loads and executes the specified file within the theme's process context.

The attack vector is Network with High attack complexity, and exploitation requires Low privileges. Successful abuse yields High impact on confidentiality, integrity, and availability. EPSS reports a probability of 0.496% with a percentile of 39.36 as of 2026-07-20.

Root Cause

The root cause is missing or insufficient sanitization of a filename parameter before it reaches a PHP inclusion function. The theme trusts request-supplied values and appends or substitutes them into a filesystem path used by include/require. Without an allowlist, canonicalization, or normalization to strip traversal sequences such as ../, the path resolves to files outside the intended directory.

Attack Vector

An authenticated attacker sends an HTTP request containing a crafted path parameter to a Billey theme endpoint that performs file inclusion. The attacker points the parameter to an arbitrary local PHP file, such as a log file poisoned with PHP code, an uploaded media file, or a session file. When the theme includes the file, PHP executes the embedded code. High complexity reflects the need to identify a suitable inclusion target and reachable file on disk. Refer to the Patchstack Vulnerability Report for technical details.

Detection Methods for CVE-2026-57790

Indicators of Compromise

HTTP requests to Billey theme endpoints containing path traversal sequences such as ../, ..%2f, or absolute paths in query parameters
Web server logs showing PHP inclusion of unexpected files under /tmp, /var/log, wp-content/uploads, or session storage directories
New or modified PHP files in wp-content/themes/billey/ or the WordPress uploads directory
Outbound connections from the PHP worker process to unfamiliar hosts following suspicious requests

Detection Strategies

Inspect WordPress access logs for parameters passing filesystem paths to Billey theme scripts
Alert on PHP include/require calls resolving to writable directories such as uploads, tmp, or log paths
Correlate authenticated low-privilege sessions with unusual file inclusion patterns targeting theme files
Use file integrity monitoring on the wp-content/themes/billey/ directory to detect tampering

Monitoring Recommendations

Enable verbose PHP error logging and forward logs to a centralized SIEM for pattern analysis
Monitor web application firewall telemetry for LFI signatures targeting WordPress themes
Track process creation events spawned by the PHP-FPM or Apache worker on WordPress hosts
Review WordPress user activity for unexpected logins that could precede exploitation

How to Mitigate CVE-2026-57790

Immediate Actions Required

Identify all WordPress sites using the Billey theme and confirm the installed version
Apply the vendor-supplied update once a fixed release above 2.1.8 becomes available
Restrict access to WordPress authenticated endpoints and rotate credentials for low-privilege accounts
Deploy a WAF rule blocking path traversal patterns and absolute file paths in Billey theme parameters

Patch Information

At the time of publication, the Patchstack Vulnerability Report tracks fix availability for Billey versions above 2.1.8. Administrators should consult Patchstack and the ThemeMove vendor channels for the current patched release and apply it via the WordPress theme updater or manual replacement.

Workarounds

Disable or remove the Billey theme until a patched version is installed
Set PHP open_basedir to constrain file inclusion to the WordPress document root
Ensure allow_url_include and allow_url_fopen are disabled in php.ini
Enforce least privilege by removing unnecessary low-privilege WordPress accounts that could reach vulnerable endpoints

bash

# Configuration example: harden php.ini against inclusion abuse
allow_url_include = Off
allow_url_fopen = Off
open_basedir = "/var/www/html:/tmp"
disable_functions = "exec,passthru,shell_exec,system,proc_open,popen"