CVE-2026-41934: Vvveb CMS RCE Vulnerability

CVE-2026-41934 Overview

CVE-2026-41934 is an authenticated remote code execution vulnerability in Vvveb content management system versions before 1.0.8.2. The flaw resides in the admin code editor and allows low-privilege authenticated users to bypass file extension restrictions. Attackers with editor, author, contributor, or site_admin roles can write a malicious .htaccess file that maps arbitrary file extensions to the PHP handler. They then upload PHP code using that mapped extension. When the file is requested over HTTP, the web server executes the attacker-controlled PHP code, resulting in full remote code execution on the host.

Critical Impact

Authenticated low-privilege users can achieve arbitrary code execution on the underlying web server, leading to complete compromise of the Vvveb installation and the hosting environment.

Affected Products

• Vvveb CMS versions prior to 1.0.8.2
• Deployments running on Apache web servers honoring .htaccess directives
• Installations exposing the admin code editor to non-administrative roles

Discovery Timeline

• 2026-05-06 - CVE CVE-2026-41934 published to NVD
• 2026-05-06 - Last updated in NVD database

Technical Details for CVE-2026-41934

Vulnerability Analysis

The vulnerability is classified under [CWE-184: Incomplete List of Disallowed Inputs]. The Vvveb admin code editor enforces a denylist of file extensions intended to prevent uploading executable PHP scripts. The denylist does not account for Apache configuration files. An authenticated user with editor, author, contributor, or site_admin privileges can write a .htaccess file inside a web-accessible directory through the editor interface.

Apache reads the attacker-supplied .htaccess at request time and applies an AddType or AddHandler directive that maps an arbitrary, otherwise-benign extension to the PHP interpreter. The attacker then writes a second file containing PHP code under that mapped extension. Issuing an HTTP request to that file causes the web server to execute the PHP payload in the context of the web server user.

Root Cause

The root cause is reliance on a static denylist of disallowed extensions instead of an allowlist of permitted file types. The editor blocks .php and similar extensions but permits writing .htaccess, allowing the attacker to redefine which extensions Apache treats as PHP. This converts a write primitive into code execution.

Attack Vector

The attack requires network access to the Vvveb admin interface and valid credentials for any role with code editor access. After authentication, the attacker writes a crafted .htaccess mapping a custom extension to the PHP handler, then writes a payload file using that extension. A subsequent unauthenticated HTTP GET request to the payload triggers execution. No user interaction is required beyond initial authentication. See the VulnCheck RCE Advisory and the GitHub Security Advisory for additional technical context.

Detection Methods for CVE-2026-41934

Indicators of Compromise

• Unexpected .htaccess files written under Vvveb web roots, particularly containing AddType, AddHandler, or SetHandler directives referencing PHP
• Newly created files with non-standard extensions in directories writable by the editor (for example .log, .txt, .inc containing PHP tags)
• HTTP access log entries showing requests to unusual file extensions returning HTTP 200 with dynamic content
• Audit log entries showing file writes by editor, author, contributor, or site_admin accounts to configuration files

Detection Strategies

• Monitor file integrity on Vvveb web roots for creation or modification of .htaccess files
• Inspect Apache configuration changes for AddHandler application/x-httpd-php or AddType application/x-httpd-php directives applied to non-PHP extensions
• Correlate Vvveb application audit logs with web server access logs to identify post-write requests that triggered PHP execution

Monitoring Recommendations

• Enable verbose logging on the Vvveb admin code editor and forward events to a centralized logging platform
• Alert on PHP child processes spawned by the web server user that initiate outbound network connections
• Track creation of files with double extensions or uncommon extensions inside content directories

How to Mitigate CVE-2026-41934

Immediate Actions Required

• Upgrade Vvveb to version 1.0.8.2 or later using the GitHub Release v1.0.8.2
• Audit all user accounts with editor, author, contributor, or site_admin roles and revoke unnecessary privileges
• Review web roots for unauthorized .htaccess files and unexpected scripts written by editor accounts
• Rotate credentials and session tokens for any account that had code editor access prior to patching

Patch Information

The vendor fixed the vulnerability in Vvveb 1.0.8.2. The fix is documented in the GitHub Commit Update, which adds restrictions preventing low-privilege roles from writing .htaccess and other server configuration files through the editor.

Workarounds

• Configure Apache to ignore .htaccess files inside Vvveb content directories by setting AllowOverride None at the virtual host level
• Restrict the admin code editor to trusted administrators only until patches are applied
• Place the Vvveb admin interface behind network-level access controls such as VPN or IP allowlisting
• Run the web server under a hardened user context with no write access to executable directories

# Apache hardening example to neutralize attacker-controlled .htaccess
<Directory /var/www/vvveb>
    AllowOverride None
    Options -ExecCGI
    php_admin_flag engine on
</Directory>