Vvveb CMS RCE: Authenticated Users Can Rename Files to Execute Code

The National Vulnerability Database has detailed a critical remote code execution vulnerability (CVE-2026-6257) in Vvveb CMS v1.0.8. The flaw lies within the media management functionality, specifically in how file renames are handled. A missing return statement allows authenticated attackers to bypass extension restrictions and rename uploaded files to .php or .htaccess. This opens the door for attackers to inject malicious Apache directives and execute arbitrary commands on the server as the www-data user.

The attacker’s calculus here is straightforward: gain initial authenticated access, then leverage this logic flaw to escalate privileges and achieve code execution. The CVSS score of 9.1 underscores the severity, as it requires only authenticated access and a network connection, with significant impact across confidentiality, integrity, and availability.

Defenders must prioritize patching or updating Vvveb CMS instances to versions that address this vulnerability. For those unable to patch immediately, scrutinizing file upload and rename logs for suspicious activity is crucial. The ability to upload seemingly benign files and then rename them to executable extensions represents a sophisticated evasion technique that bypasses typical file type filters.