Medium severity · published Sep 8, 2026
CVE-2026-54611
InstantCMS has Remote Code Execution in package installer
5.5
CVSS
0.7%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:H
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Confidentiality
None
Integrity
Low
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.7% · higher than 52% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
IC
icms2 · instantsoft
< 2.18.2 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-54611
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-54611
github.com
https://github.com/instantsoft/icms2/commit/44f3a9d04a3207c82cdc756599cbdf084a02858f
github.com
https://github.com/instantsoft/icms2/security/advisories/GHSA-vvgv-h28h-p2m5
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