CVE-2026-25199
Apache CloudStack: Proxmox Extension Allows Unauthorized Cross-Tenant Instance Access
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.
INFO
Published Date :
May 8, 2026, 1:16 p.m.
Last Modified :
Oct. 26, 2026, 7:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | CRITICAL | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Upgrade to version 4.22.0.1.
- Prevent proxmox_vmid edits via global configuration.
- Add proxmox_vmid to user.vm.denied.details.
Public PoC/Exploit Available at Github
CVE-2026-25199 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-25199.
| URL | Resource |
|---|---|
| https://lists.apache.org/thread/n8mt5b7wkpysstb8w7rr9f02kc5cq2xm | Mailing List Vendor Advisory |
| http://www.openwall.com/lists/oss-security/2026/05/09/7 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-25199 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-25199
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Repositorio de Evidencias obtenidas en el trabajo practico N°3 de OSINT al ARSAT
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-25199 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-25199 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Oct. 26, 2026
Action Type Old Value New Value Added Translation Title: Apache CloudStack de Apache Software Foundation, Description: Las instancias desplegadas a través de la extensión Proxmox permiten el acceso no autorizado a instancias pertenecientes a otros inquilinos. Este problema afecta a Apache CloudStack: desde la versión 4.21.0.0 hasta la 4.22.0.0. La extensión Proxmox para CloudStack utiliza incorrectamente una configuración de instancia editable por el usuario, proxmox_vmid, para asociar instancias de CloudStack con máquinas virtuales Proxmox. Debido a que este valor no está restringido ni validado contra la propiedad del inquilino y los ID de VM de Proxmox son predecibles, un atacante no privilegiado puede modificar la configuración para hacer referencia a una VM perteneciente a otra cuenta. Esto permite el acceso no autorizado entre inquilinos y habilita el control total sobre la VM objetivo, incluyendo el inicio, la detención y la destrucción de la máquina virtual. Se recomienda a los usuarios actualizar a la versión 4.22.0.1, que corrige este problema. Como solución alternativa para las instalaciones existentes, se puede evitar que los usuarios editen el detalle de instancia proxmox_vmid añadiendo este nombre de detalle al parámetro de configuración global - user.vm.denied.details. -
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'Apache Software Foundation', 'product': 'Apache CloudStack', 'versions': [{'status': 'affected', 'version': '4.21.0', 'versionType': 'semver', 'lessThanOrEqual': '4.22.0'}], 'defaultStatus': 'unaffected'}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-25199', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-05-08T17:24:28.485753Z'} -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
May. 09, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/05/09/7 -
Initial Analysis by [email protected]
May. 08, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:apache:cloudstack:*:*:*:*:*:*:*:* versions from (including) 4.21.0.0 up to (excluding) 4.22.0.1 Added Reference Type Apache Software Foundation: https://lists.apache.org/thread/n8mt5b7wkpysstb8w7rr9f02kc5cq2xm Types: Mailing List, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
May. 08, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N -
New CVE Received by [email protected]
May. 08, 2026
Action Type Old Value New Value 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. Added CWE CWE-200 Added Reference https://lists.apache.org/thread/n8mt5b7wkpysstb8w7rr9f02kc5cq2xm