CVE-2026-66797: Apache Cloudstack

Medium severity, CVSS 5.4. EPSS: 0.5% chance of exploitation in the next 30 days.

Improper access control in CloudStack's annotation functionality allows unauthorized comment creation and disclosure. The addAnnotation and listAnnotation APIs perform an ownership check when an entity's UUID is specified, but fail to honor its result correctly. This lets any authenticated user write annotations to, and disclose existing annotations/comments on, an entity they don't own by simply supplying its UUID. This issue affects Apache CloudStack: from 4.15.0.0 through 4.20.3.0 and from 4.21.0.0 through 4.22.1.0. Users are recommended to upgrade to version 4.20.3.1 or 4.22.1.1 or later, which fixes the issue.

Affected products

• Apache Cloudstack: from 4.15.0.0, before 4.20.3.1 (fixed in 4.20.3.1); from 4.21.0.0, before 4.22.1.1 (fixed in 4.22.1.1)

Published 2026-08-21. Last modified 2026-08-27.