How severe is CVE-2025-66547?

CVE-2025-66547 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2025-66547 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-66547?

CVE-2025-66547 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-2025-66547?

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

Does CVE-2025-66547 have an EU (EUVD) identifier?

Yes. CVE-2025-66547 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201447.

When was CVE-2025-66547 published?

CVE-2025-66547 was published on 2025-12-05 and last updated on 2026-06-17.

CVE-2025-66547

CVE-2025-66547 is a medium-severity vulnerability in Nextcloud Nextcloud Server with a CVSS 3.x base score of 4.3. 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-639.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
EPSS exploit prediction: 0% (15th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-201447
Weakness: CWE-639
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 and Enterprise Server prior to 31.0.1, non-privileged users can modify tags on files they should not have access to via bulk tagging. This vulnerability is fixed in 31.0.1.

Frequently asked questions

What is CVE-2025-66547?: Nextcloud Server is a self hosted personal cloud system. In Nextcloud Server and Enterprise Server prior to 31.0.1, non-privileged users can modify tags on files they should not have access to via bulk tagging. This vulnerability is fixed in 31.0.1.
How severe is CVE-2025-66547?: CVE-2025-66547 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2025-66547 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-66547?: CVE-2025-66547 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-2025-66547?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-66547 have an EU (EUVD) identifier?: Yes. CVE-2025-66547 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201447.
When was CVE-2025-66547 published?: CVE-2025-66547 was published on 2025-12-05 and last updated on 2026-06-17.

References

Affected products (2)

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

More vulnerabilities in Nextcloud Nextcloud Server

CVE-2021-22915 — Critical (CVSS 9.8): Nextcloud server before 19.0.11, 20.0.10, 21.0.2 is vulnerable to brute force attacks due to lack of inclusion of IPv6…
CVE-2021-32802 — Critical (CVSS 9.3): Nextcloud server is an open source, self hosted personal cloud. Nextcloud supports rendering image previews for user…
CVE-2023-26482 — Critical (CVSS 9.0): Nextcloud server is an open source home cloud implementation. In affected versions a missing scope validation allowed…
CVE-2021-32688 — High (CVSS 8.8): Nextcloud Server is a Nextcloud package that handles data storage. Nextcloud Server supports application specific…
CVE-2018-3775 — High (CVSS 8.8): Improper Authentication in Nextcloud Server prior to version 12.0.3 would allow an attacker that obtained user…
CVE-2023-35172 — High (CVSS 8.7): NextCloud Server and NextCloud Enterprise Server provide file storage for Nextcloud, a self-hosted productivity…

All CVEs affecting Nextcloud Nextcloud Server →

Other CWE-639 (Authorization Bypass Through User-Controlled Key (IDOR)) vulnerabilities

CVE-2025-40805 — Critical (CVSS 10.0): Affected devices do not properly enforce user authentication on specific API endpoints. This could facilitate an…
CVE-2024-45032 — Critical (CVSS 10.0): A vulnerability has been identified in Industrial Edge Management Pro (All versions < V1.9.5), Industrial Edge…
CVE-2026-34037 — Critical (CVSS 9.9): Coolify is an open-source and self-hostable tool for managing servers, applications, and databases. Prior to…
CVE-2026-52782 — Critical (CVSS 9.9): OpenProject is open-source, web-based project management software. Prior to 17.3.3 and 17.4.1, there is an IDOR through…
CVE-2026-45552 — Critical (CVSS 9.9): Roxy-WI is a web interface for managing Haproxy, Nginx, Apache and Keepalived servers. In versions 8.2.6.4 and prior,…
CVE-2026-29200 — Critical (CVSS 9.9): A critical IDOR vulnerability has been discovered in Comet Backup affecting all versions from 20.11.0 to 26.1.1 and…

Browse all CWE-639 (Authorization Bypass Through User-Controlled Key (IDOR)) vulnerabilities →