CVE-2026-25199

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.

CVSS v3.1 Score

9.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0004

Probability of exploitation

0.11%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-200 CWE-200

Affected Products

Vendor	Product	Versions
apache	cloudstack	4.21.0.0 — 4.22.0.1

References

Advisories & Patches

https://lists.apache.org/thread/n8mt5b7wkpysstb8w7rr9f02kc5cq2xm

Other References

http://www.openwall.com/lists/oss-security/2026/05/09/7

Frequently Asked Questions

What is CVE-2026-25199? +

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. It has a CVSS v3.1 base score of 9.1 (CRITICAL).

How severe is CVE-2026-25199? +

CVE-2026-25199 has a CVSS v3.1 score of 9.1 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0004, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-25199? +

CVE-2026-25199 affects products from apache, specifically: cloudstack. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-25199? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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