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CVE-2026-21861: basercms vulnerability
CVE-2026-21861: critical vulnerability affecting basercms. Check CVSS, KEV status, business impact and recommended administrator actions.
- CVSS
- 9.1 CRITICAL
- EPSS
- 81.06%
- Known exploited
- not in KEV
- Product
- basercms
What is known
baserCMS is a website development framework. Prior to version 5.2.3, baserCMS contains an OS command injection vulnerability in the core update functionality. An authenticated administrator can execute arbitrary OS commands on the server due to improper handling of user-controlled input that is directly passed to exec() without sufficient validation or escaping. This issue has been patched in version 5.2.3.
Business impact
Successful exploitation of CVE-2026-21861, a critical vulnerability (CVSS 9.1) affecting basercms, may affect the confidentiality, integrity or availability of the vulnerable environment. The exact impact depends on the installed version, exposed interfaces and deployment configuration.
Recommended administrator action
Confirm whether basercms is present and compare installed versions with the vendor advisory and NVD record. Apply the vendor patch or documented mitigation; until remediation is complete, reduce exposure of affected interfaces, review relevant logs and monitor for indicators of exploitation. DataHouse can support version verification, managed patching, network exposure reduction, log review and backup validation for dedicated, cloud and colocated environments.