Description
InstantCMS is a free and open source content management system. Versions prior to 2.18.2 have a Remote Code Execution (RCE) issue that allows remote authenticated attackers to execute any PHP code via the component installer. It is possible to upload a malicious component into the server, however, it won't be installed, but upload files will be executed. Normally all php files in upload folder are not executed, however, by uploading custom .htaccess it becomes possible. Version 2.18.2 contains a fix.
References3
Metrics
- CVSS 3.1
-
5.5
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:H - EPSS — exploit probability
- 1% percentile: 52 · as of 3 November 2026
- CWE
- CWE-94CWE-434
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.