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CVE-2025-66552: Nextcloud Server is a self hosted personal cloud system

21
Routine
MEDIUM 4.3UPGRADE

CVE-2025-66552 is a medium-severity flaw (CVSS 4.3) affecting nextcloud server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Nextcloud Server is a self hosted personal cloud system. In Nextcloud Server and Enterprise Server prior to 30.0.9 and 31.0.1, incorrect path handling with groupfolders caused the admin_audit app to not properly log all actions on files and folders inside groupfolders. This vulnerability is fixed in Nextcloud Server and Enterprise Server prior to 30.0.9 and 31.0.1.

Why this priority

  • No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score4.3 (Medium)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededLow
User interactionNone
EPSS exploit chance0.3% (top 76%)
CISA exploited listNo
WeaknessCWE-778
Published2025-12-05
Last modified2026-10-18
Publisher (CNA): GitHub, Inc. · Vendor: nextcloud

Share: LinkedIn · X · Reddit

Last updated 2026-10-18 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

nextcloud nextcloud server UPGRADE
Affected: >= 30.0.0 and < 30.0.9 · >= 31.0.0 and < 31.0.1
Fixed in: 30.0.9, 31.0.1
Safe to downgrade to: a release before 30.0.0
1. Check installed version
apt-cache policy nextcloud-server || rpm -q nextcloud-server || nextcloud-server --version
2. UPGRADE to 30.0.9 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade nextcloud-server
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade nextcloud-server
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 30.0.0 (Debian / Ubuntu)
apt-cache madison nextcloud-server sudo apt install nextcloud-server=<VERSION_BEFORE_30.0.0> sudo apt-mark hold nextcloud-server
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list nextcloud-server sudo dnf downgrade nextcloud-server-<VERSION_BEFORE_30.0.0> sudo dnf versionlock add nextcloud-server
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-2025-66552?

nextcloud server: upgrade to 30.0.9, 31.0.1. Exact commands for each OS are on this page.

Is CVE-2025-66552 being exploited?

CVE-2025-66552 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-2025-66552 affect?

CVE-2025-66552 affects nextcloud server. Severity is medium (CVSS 4.3). Nextcloud Server is a self hosted personal cloud system. In Nextcloud Server and Enterprise Server prior to 30.0.9 and 31.0.1, incorrect path handling with groupfolders caused the admin_audit app to not properly log all actions on files and

How urgent is CVE-2025-66552?

Priority 21/100. No elevated risk signals yet.

Software pages

Nextcloud vulnerabilities

Related CVEs

References

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