CVE-2026-25199
Apache CloudStack: Proxmox Extension Allows Unauthorized Cross-Tenant Instance Access
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Apache CloudStack: Proxmox Extension Allows Unauthorized Cross-Tenant Instance Access
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.
- Record
CVE-2026-25199- CVSS 3.1
- 9.1 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-200
- Updated
- 2026-11-02
EUVDEUVD-2026-28550
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.
- Record
EUVD-2026-28550- CVSS 3.1
- 9.1 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-whfq-93mc-cv6g
Instances deployed via the Proxmox extension allow unauthorized access to instances belonging to...
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.
- Record
GHSA-whfq-93mc-cv6g- CVSS 3.1
- 9.1 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-200
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-25199- CVSS 3.1
- 9.1 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-200
- Updated
- 2026-11-02
OSV
Apache CloudStack: Proxmox Extension Allows Unauthorized Cross-Tenant Instance Access
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.
- Record
CVE-2026-25199- CVSS 3.1
- 9.1 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-200
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-25199 is a critical vulnerability (CVSS 9.1) in Apache Cloudstack, published May 8, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.50%, the 43rd percentile. No source names a fixed version.