What’s Vulnerable › Vulnerabilities

CVE-2026-54611: InstantCMS has Remote Code Execution in package installer

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-08 · updated 2026-09-09
• Weakness: CWE-94

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.

Affected products

• instantsoft/icms2: before 2.18.2

References

• https://github.com/instantsoft/icms2/commit/44f3a9d04a3207c82cdc756599cbdf084a02858f
• https://github.com/instantsoft/icms2/security/advisories/GHSA-vvgv-h28h-p2m5
• https://github.com/instantsoft/icms2/security/advisories/GHSA-vvgv-h28h-p2m5

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