Skip to content
Fencer Intel
critical 9.1

CVE-2026-25199 json

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

published 6mo ago modified 14d ago also EUVD-2026-28550

cvss
9.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 43%
public exploits
0
none known

Summary

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.

Patch / fix

  • apache cloudstack 4.22.0.1

Is CVE-2026-25199 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
6mo ago

Exploit prediction

0.50% chance of exploitation in the next 30 days, higher than 43% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CNA 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

  • Apache Software Foundation Apache CloudStack

Classification

Weakness
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.