CVE-2025-66171 | Apache CloudStack: Any user can create a new VM from backups they should not have access to

The CloudStack Backup plugin has an improper access logic in versions 4.21.0.0 and 4.22.0.0. Anyone with authenticated user-account access in CloudStack 4.21.0.0+ environments, where this plugin is enabled and have access to specific APIs can create new VMs using backups of any other user of the environment. Backup plugin users using CloudStack 4.21.0.0+ are recommended to upgrade to CloudStack version 4.22.0.1, which fixes this issue.

Published: 2026-05-08 Last update: 2026-05-12 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-66171 is rated Low Risk (26.5/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.01%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-66171

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-09 — 0.01% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-66171

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2025-66171

GitHub Security Advisory for CVE-2025-66171

GHSA-5f56-5m8x-gjf9 · Severity: medium — The CloudStack Backup plugin has an improper access logic in versions 4.21.0.0 and 4.22.0.0....

Affected software / configurations for CVE-2025-66171

Vendor Product Version Raw CPE
apache cloudstack >= 4.21.0.0, < 4.22.0.1 cpe:2.3:a:apache:cloudstack:*:*:*:*:*:*:*:*

References for CVE-2025-66171

URL Tags
https://lists.apache.org/thread/n8mt5b7wkpysstb8w7rr9f02kc5cq2xm Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2026/05/09/2 Mailing List Third Party Advisory
cvelogic Threat Intelligence