How severe is CVE-2025-66510?

CVE-2025-66510 has a CVSS 3.x base score of 4.5, rated medium severity. It is exploitable over network with low attack complexity, requires high privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2025-66510 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (22nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-66510?

CVE-2025-66510 primarily affects Nextcloud Nextcloud Server. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2025-66510?

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

Does CVE-2025-66510 have an EU (EUVD) identifier?

Yes. CVE-2025-66510 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201451.

When was CVE-2025-66510 published?

CVE-2025-66510 was published on 2025-12-05 and last updated on 2026-06-17.

CVE-2025-66510

CVE-2025-66510 is a medium-severity vulnerability in Nextcloud Nextcloud Server with a CVSS 3.x base score of 4.5. 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 4.5)
EPSS exploit prediction: 0% (22nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-201451
Weakness: CWE-359
Affected product: Nextcloud Nextcloud Server
Published: 2025-12-05
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2025-66510?: 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.
How severe is CVE-2025-66510?: CVE-2025-66510 has a CVSS 3.x base score of 4.5, rated medium severity. It is exploitable over network with low attack complexity, requires high privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2025-66510 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (22nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-66510?: CVE-2025-66510 primarily affects Nextcloud Nextcloud Server. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2025-66510?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-66510 have an EU (EUVD) identifier?: Yes. CVE-2025-66510 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201451.
When was CVE-2025-66510 published?: CVE-2025-66510 was published on 2025-12-05 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:enterprise:*:*:*
cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:-:*:*:*

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