How severe is CVE-2025-66171?

CVE-2025-66171 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2025-66171 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-66171?

CVE-2025-66171 affects Apache Cloudstack. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-66171?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2025-66171 have an EU (EUVD) identifier?

Yes. CVE-2025-66171 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-209741.

When was CVE-2025-66171 published?

CVE-2025-66171 was published on 2026-05-08 and last updated on 2026-06-17.

CVE-2025-66171

CVE-2025-66171 is a medium-severity vulnerability in Apache Cloudstack with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-359.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 1% (41st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-209741
Weakness: CWE-359
Affected product: Apache Cloudstack
Published: 2026-05-08
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2025-66171?: 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.
How severe is CVE-2025-66171?: CVE-2025-66171 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2025-66171 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-66171?: CVE-2025-66171 affects Apache Cloudstack. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-66171?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-66171 have an EU (EUVD) identifier?: Yes. CVE-2025-66171 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-209741.
When was CVE-2025-66171 published?: CVE-2025-66171 was published on 2026-05-08 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:apache:cloudstack:*:*:*:*:*:*:*:*

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