Vvveb Denylist Bypass Allowing PHP File Upload

Executive Summary

CVE-2026-126380 is a critical Remote Code Execution (RCE) vulnerability in Vvveb versions before 1.0.9.0. It stems from a denylist bypass in the media upload feature where '.phar' is incorrectly configured with a leading dot. This allows authenticated administrators to upload malicious .phar PHP files. Attackers can exploit this by uploading a GIF magic-byte polyglot webshell, bypassing binary inspection and executing arbitrary OS commands as the web-server user.

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Detection Guidance

Check for unauthorized .phar files in upload directories, especially those with GIF magic bytes. Inspect system/traits/media.php for the denylist bypass where '.phar' is incorrectly configured. Use commands like 'find /path/to/uploads -name "*.phar" -type f' to locate suspicious files.

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Impact Analysis

If exploited, this vulnerability allows attackers with admin access to upload malicious files, execute arbitrary commands on the server, steal database credentials, or install persistent backdoors. The impact includes full server compromise, data theft, and potential disruption of services. The high CVSS scores (9.4 v4.0, 9.1 v3.1) reflect the severe confidentiality, integrity, and availability risks.

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Compliance Impact

This vulnerability likely violates compliance requirements under GDPR and HIPAA due to unauthorized data access, potential data breaches, and lack of proper access controls. GDPR mandates protection of personal data, while HIPAA requires safeguards for protected health information. Exploitation could lead to unauthorized data exposure, triggering regulatory penalties and legal consequences.

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Mitigation Strategies

Upgrade Vvveb to version 1.0.9.0 or later. Remove the leading dot from '.phar' in the denylist in system/traits/media.php. Ensure PHP does not process .phar files by removing the association in your web server configuration.

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