CVE-2026-27891

Description

### Summary A Critical vulnerability exists in the `Plugins::add()` function. The system fails to properly validate the file paths within uploaded ZIP archives. This allows an attacker to perform a Zip Slip attack, leading to Arbitrary File Write and Remote Code Execution (RCE) by overwriting sensitive .php files outside the designated plugins directory. ### Details The vulnerability is located in Plugins.php. While the `testZipFile` function attempts to validate that the ZIP contains only one root folder, it does not sanitize or validate the individual file paths within that folder. ```js // Vulnerable logic in Plugins.php for ($index = 0; $index < $zipFile->numFiles; $index++) { $data = $zipFile->statIndex($index); $path = explode('/', $data['name']); if (count($path) > 1) { $folders[$path[0]] = $path[0]; } } ``` An attacker can bypass this check by naming a file `ValidPluginName/../../shell.php`. The explode function will see ValidPluginName as the root folder, satisfying the `count($folders) != 1` check. However, during extraction, the `../../` sequence triggers a path traversal, allowing the file to be written anywhere the web server has permissions the root directory. ### PoC Prepare Malicious ZIP: Use a tool (like evilarc) or a script to create a ZIP file where one of the entries is named: `MyPlugin/../../rce.php` Inject Payload: Inside rce.php, put a simple shell: `<?php system($_GET['cmd']); ?>` Upload: Navigate to the "Add Plugin" section in FacturaScripts and upload the malicious ZIP. Execution: Access the shell via https://target.com/rce.php?cmd=whoami. ### Impact Confidentiality: High (Attacker can read all database configs and files). Integrity: High (Attacker can modify any file on the server). Availability: High (Attacker can delete the entire installation). > https://github.com/ZeroXJacks/CVEs/blob/main/2026/CVE-2026-27891.md

How to fix CVE-2026-27891

No fixed version has been published yet. Mitigate by removing the affected package or applying upstream guidance from the references below.

• —no fix listed

Is CVE-2026-27891 being exploited?

Low — EPSS is 0.2%, meaning exploitation activity has not been observed at scale.