{"id":"CVE-2026-25199","aliases":["EUVD-2026-28550","GHSA-whfq-93mc-cv6g"],"status":"published","title":"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.\n\n\n\n\nThis issue affects Apache CloudStack: from 4.21.0.0 through 4.22.0.0.\n\n\n\n\nThe 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.\n\n\n\n\nUsers are recommended to upgrade to version 4.22.0.1, which fixes this issue.\n\n\n\n\nAs 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.","severity":{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"critical","assessor":"adp","from":"cve"},"epss":{"day":"2026-11-08","score":0.005,"percentile":0.43123,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-200"],"published":"2026-05-08T12:22:56Z","modified":"2026-11-08T02:47:22Z","products":[{"vendor":"apache","product":"cloudstack"},{"vendor":"apache software foundation","product":"apache cloudstack"}],"references":[{"url":"https://lists.apache.org/thread/n8mt5b7wkpysstb8w7rr9f02kc5cq2xm","tags":["vendor-advisory","Mailing List","Vendor Advisory","advisory"]},{"url":"http://www.openwall.com/lists/oss-security/2026/05/09/7","tags":["web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-25199","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-whfq-93mc-cv6g"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/25xxx/CVE-2026-25199.json","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-25199","title":"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.\n\n\n\n\nThis issue affects Apache CloudStack: from 4.21.0.0 through 4.22.0.0.\n\n\n\n\nThe 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.\n\n\n\n\nUsers are recommended to upgrade to version 4.22.0.1, which fixes this issue.\n\n\n\n\nAs 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.","status":"published","published":"2026-05-08T12:22:56.226Z","modified":"2026-05-09T06:43:07.02Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"critical","assessor":"adp"}],"cwes":["CWE-200"],"updated_at":"2026-11-02T13:41:30.911526Z"}],"euvd":[{"id":"EUVD-2026-28550","description":"Instances deployed via the Proxmox extension allow unauthorized access to instances belonging to other tenants.\n\n\n\n\nThis issue affects Apache CloudStack: from 4.21.0.0 through 4.22.0.0.\n\n\n\n\nThe 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.\n\n\n\n\nUsers are recommended to upgrade to version 4.22.0.1, which fixes this issue.\n\n\n\n\nAs 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.","status":"published","published":"2026-05-08T12:22:56Z","modified":"2026-05-09T06:43:07Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"critical"}],"updated_at":"2026-11-02T19:05:14.089367Z"}],"ghsa":[{"id":"GHSA-whfq-93mc-cv6g","title":"Instances deployed via the Proxmox extension allow unauthorized access to instances belonging to...","description":"Instances deployed via the Proxmox extension allow unauthorized access to instances belonging to other tenants.\n\n\n\n\nThis issue affects Apache CloudStack: from 4.21.0.0 through 4.22.0.0.\n\n\n\n\nThe 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.\n\n\n\n\nUsers are recommended to upgrade to version 4.22.0.1, which fixes this issue.\n\n\n\n\nAs 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.","status":"published","published":"2026-05-08T15:31:20Z","modified":"2026-05-09T09:32:47Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"critical"}],"cwes":["CWE-200"],"updated_at":"2026-11-02T15:07:58.197878Z"}],"nvd":[{"id":"CVE-2026-25199","description":"Instances deployed via the Proxmox extension allow unauthorized access to instances belonging to other tenants.\n\n\n\n\nThis issue affects Apache CloudStack: from 4.21.0.0 through 4.22.0.0.\n\n\n\n\nThe 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.\n\n\n\n\nUsers are recommended to upgrade to version 4.22.0.1, which fixes this issue.\n\n\n\n\nAs 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.","status":"published","published":"2026-05-08T13:16:36.273Z","modified":"2026-10-26T19:10:00.163Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"critical","assessor":"secondary"}],"cwes":["CWE-200"],"updated_at":"2026-11-02T14:12:17.842772Z"}],"osv":[{"id":"CVE-2026-25199","title":"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.\n\n\n\n\nThis issue affects Apache CloudStack: from 4.21.0.0 through 4.22.0.0.\n\n\n\n\nThe 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.\n\n\n\n\nUsers are recommended to upgrade to version 4.22.0.1, which fixes this issue.\n\n\n\n\nAs 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.","status":"published","published":"2026-05-08T12:22:56.226Z","modified":"2026-11-08T02:47:22.239760655Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"critical"}],"cwes":["CWE-200"],"updated_at":"2026-11-08T02:57:30.447698Z"}]}}