How severe is CVE-2025-66512?

CVE-2025-66512 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity low, and availability low.

Is CVE-2025-66512 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-2025-66512?

CVE-2025-66512 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-2025-66512?

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

Does CVE-2025-66512 have an EU (EUVD) identifier?

Yes. CVE-2025-66512 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201449.

When was CVE-2025-66512 published?

CVE-2025-66512 was published on 2025-12-05 and last updated on 2026-06-17.

CVE-2025-66512

CVE-2025-66512 is a medium-severity vulnerability in Nextcloud Nextcloud Server with a CVSS 3.x base score of 5.4. 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-79.

Key facts

Severity: Medium (CVSS 3.x base score 5.4)
EPSS exploit prediction: 0% (15th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-201449
Weakness: CWE-79
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 Server Enterprise prior to 31.0.12 and 32.0.3, a missing sanitization allowed malicious users to circumvent the content security policy when a malicious user manages to trick a user it viewing an uploaded SVG outside of the Nextcloud Servers web page.

Frequently asked questions

What is CVE-2025-66512?: Nextcloud Server is a self hosted personal cloud system. In Nextcloud Server and Server Enterprise prior to 31.0.12 and 32.0.3, a missing sanitization allowed malicious users to circumvent the content security policy when a malicious user manages to trick a user it viewing an uploaded SVG outside of the Nextcloud Servers web page.
How severe is CVE-2025-66512?: CVE-2025-66512 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity low, and availability low.
Is CVE-2025-66512 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-2025-66512?: CVE-2025-66512 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-2025-66512?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-66512 have an EU (EUVD) identifier?: Yes. CVE-2025-66512 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201449.
When was CVE-2025-66512 published?: CVE-2025-66512 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:*:*:*

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