CVE-2026-54611

InstantCMS has Remote Code Execution in package installer

State: Published
Severity: 5.5 Medium
Published: Sep 8, 2026
Updated: Sep 9, 2026
Reserved: Jun 15, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	5.5 Medium	CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:H	GitHub_M

Weaknesses

CWE-94 Improper Control of Generation of Code ('Code Injection')
CWE-434 Unrestricted Upload of File with Dangerous Type

Affected Products

Product	Versions
icms2instantsoft	< 2.18.2Affected

References

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