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CVE-2025-66510: Nextcloud Server is a self hosted personal cloud system

23
Routine
MEDIUM 4.5UPGRADE

CVE-2025-66510 is a medium-severity flaw (CVSS 4.5) 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 prior to 31.0.10 and 32.0.1 and Nextcloud Enterprise Server prior to 28.0.14.11, 29.0.16.8, 30.0.17.3, and 31.0.10, contacts search allowed to retrieve personal data of other users (emails, names, identifiers) without proper access control. This allows an authenticated user to retrieve information about accounts that are not related or added as contacts.

Why this priority

  • No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score4.5 (Medium)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededHigh
User interactionRequired
EPSS exploit chance0.4% (top 71%)
CISA exploited listNo
WeaknessCWE-359
Published2025-12-05
Last modified2026-10-18
Publisher (CNA): GitHub, Inc. · Vendor: nextcloud

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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: >= 28.0.0 and < 28.0.14.11 · >= 29.0.0 and < 29.0.16.8 · >= 30.0.0 and < 30.0.17.3 · >= 31.0.0 and < 31.0.10 · >= 32.0.0 and < 32.0.1
Fixed in: 28.0.14.11, 29.0.16.8, 30.0.17.3, 31.0.10, 32.0.1
Safe to downgrade to: a release before 28.0.0
1. Check installed version
apt-cache policy nextcloud-server || rpm -q nextcloud-server || nextcloud-server --version
2. UPGRADE to 28.0.14.11 (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 28.0.0 (Debian / Ubuntu)
apt-cache madison nextcloud-server sudo apt install nextcloud-server=<VERSION_BEFORE_28.0.0> 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_28.0.0> 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-2025-66510?

nextcloud server: upgrade to 28.0.14.11, 29.0.16.8, 30.0.17.3, 31.0.10, 32.0.1. Exact commands for each OS are on this page.

Is CVE-2025-66510 being exploited?

CVE-2025-66510 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-2025-66510 affect?

CVE-2025-66510 affects nextcloud server. Severity is medium (CVSS 4.5). Nextcloud Server is a self hosted personal cloud system. In Nextcloud Server prior to 31.0.10 and 32.0.1 and Nextcloud Enterprise Server prior to 28.0.14.11, 29.0.16.8, 30.0.17.3, and 31.0.10, contacts search allowed to retrieve personal da

How urgent is CVE-2025-66510?

Priority 23/100. No elevated risk signals yet.

Software pages

Nextcloud vulnerabilities

Related CVEs

References

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