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CVE-2025-66171: The CloudStack Backup plugin has an improper access logic in versions 4.21.0.0 and 4.22.0.0

39
Routine
MEDIUM 6.5WATCHLISTUPGRADE

CVE-2025-66171 is a medium-severity flaw (CVSS 6.5) affecting cloudstack. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

  • On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score6.5 (Medium)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededLow
User interactionNone
EPSS exploit chance0.5% (top 55%)
CISA exploited listNo
WeaknessCWE-359
Published2026-05-08
Last modified2026-10-07
Publisher (CNA): Apache Software Foundation · Vendor: apache

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Last updated 2026-10-07 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

apache cloudstack UPGRADE
Affected: >= 4.21.0.0 and < 4.22.0.1
Fixed in: 4.22.0.1
Safe to downgrade to: a release before 4.21.0.0
1. Check installed version
apt-cache policy cloudstack || rpm -q cloudstack || cloudstack --version
2. UPGRADE to 4.22.0.1 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade cloudstack
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade cloudstack
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
3. If no update is available yet, DOWNGRADE to a release before 4.21.0.0 (Debian / Ubuntu)
apt-cache madison cloudstack sudo apt install cloudstack=<VERSION_BEFORE_4.21.0.0> sudo apt-mark hold cloudstack
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list cloudstack sudo dnf downgrade cloudstack-<VERSION_BEFORE_4.21.0.0> sudo dnf versionlock add cloudstack
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-66171?

cloudstack: upgrade to 4.22.0.1. Exact commands for each OS are on this page.

Is CVE-2025-66171 being exploited?

CVE-2025-66171 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-66171 affect?

CVE-2025-66171 affects cloudstack. Severity is medium (CVSS 6.5). 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 c

How urgent is CVE-2025-66171?

Priority 39/100. On your watchlist

Related CVEs

References

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