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CVE

CVE-2026-25199

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

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.

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This issue affects Apache CloudStack: from 4.21.0.0 through 4.22.0.0.

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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.

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

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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.

Package Versions Affected

Package Version
patch Availability
No items found.

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CVSS Version

Severity
Base Score
CVSS Version
Score Vector
C
H
U
9.1
-
3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
C
H
U
0
-
3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
C
H
U
-

Related Resources

No items found.

References

http://www.openwall.com/lists/oss-security/2026/05/09/7, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/25xxx/CVE-2026-25199.json, https://lists.apache.org/thread/n8mt5b7wkpysstb8w7rr9f02kc5cq2xm, https://nvd.nist.gov/vuln/detail/CVE-2026-25199

Severity

9.1

CVSS Score
0
10

Basic Information

Base CVSS
9.1
EPSS Probability
0.005%
EPSS Percentile
0.40863%
Introduced Version
f9513b47bf8cda46c2cee7e31d4d662346bc7399
Fix Available
71f47d61304d1a05627bc335c8d35d7ef1040fe1

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