CVE-2026-25199

Apache CloudStack: Proxmox Extension Allows Unauthorized Cross-Tenant Instance Access

Published May 8, 2026 CVSS 3.1 · 9.1 Critical EPSS < 1% KEV · Not listed
Description
Instances deployed via the Proxmox extension allow unauthorized access to instances belonging to other tenants.




This issue affects Apache CloudStack: from 4.21.0.0 through 4.22.0.0.




The Proxmox extension for CloudStack improperly uses a user-editable instance setting, proxmox_vmid, to associate CloudStack instances with Proxmox virtual machines. Because this value is not restricted or validated against tenant ownership and Proxmox VM IDs are predictable, a non-privileged attacker can modify the setting to reference a VM belonging to another account. This allows unauthorized cross-tenant access and enables full control over the targeted VM, including starting, stopping, and destroying the virtual machine.




Users are recommended to upgrade to version 4.22.0.1, which fixes this issue.




As a workaround for the existing installations, editing of the proxmox_vmid instance detail by users can be prevented by adding this detail name to the global configuration parameter - user.vm.denied.details.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

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History
Type Values Removed Values Added
CPEs cpe:2.3:a:apache:cloudstack:*:*:*:*:*:*:*:*
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Apache
Apache cloudstack
Vendors & Products Apache
Apache cloudstack
Type Values Removed Values Added
Description Instances deployed via the Proxmox extension allow unauthorized access to instances belonging to other tenants. This issue affects Apache CloudStack: from 4.21.0.0 through 4.22.0.0. The Proxmox extension for CloudStack improperly uses a user-editable instance setting, proxmox_vmid, to associate CloudStack instances with Proxmox virtual machines. Because this value is not restricted or validated against tenant ownership and Proxmox VM IDs are predictable, a non-privileged attacker can modify the setting to reference a VM belonging to another account. This allows unauthorized cross-tenant access and enables full control over the targeted VM, including starting, stopping, and destroying the virtual machine. Users are recommended to upgrade to version 4.22.0.1, which fixes this issue. As a workaround for the existing installations, editing of the proxmox_vmid instance detail by users can be prevented by adding this detail name to the global configuration parameter - user.vm.denied.details.
Title Apache CloudStack: Proxmox Extension Allows Unauthorized Cross-Tenant Instance Access
Weaknesses CWE-200
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
apache
Published
Updated
May 9, 2026, 6:43 AM
Reserved
Jan 30, 2026, 4:45 AM
Status
Modified
Published
May 8, 2026, 1:16 PM
Modified
Oct 26, 2026, 7:10 PM