How severe is CVE-2025-66554?

CVE-2025-66554 has a CVSS 3.x base score of 3.5, rated low severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2025-66554 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (11th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-66554?

CVE-2025-66554 affects Nextcloud Contacts. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-66554?

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

Does CVE-2025-66554 have an EU (EUVD) identifier?

Yes. CVE-2025-66554 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201461.

When was CVE-2025-66554 published?

CVE-2025-66554 was published on 2025-12-05 and last updated on 2026-06-17.

CVE-2025-66554

CVE-2025-66554 is a low-severity vulnerability in Nextcloud Contacts with a CVSS 3.x base score of 3.5. 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-79.

Key facts

Severity: Low (CVSS 3.x base score 3.5)
EPSS exploit prediction: 0% (11th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-201461
Weakness: CWE-79
Affected product: Nextcloud Contacts
Published: 2025-12-05
Last modified: 2026-06-17

Description

Contacts app for Nextcloud easily syncs contacts from various devices with your Nextcloud and allows editing. Prior to 5.5.4, 6.0.6, and 7.2.5, a malicious user was able to modify their organisation and title field to load additional CSS files. Javascript and other options were correctly blocked by the content security policy of the Nextcloud Server code. This vulnerability is fixed in 5.5.4, 6.0.6, and 7.2.5.

Frequently asked questions

What is CVE-2025-66554?: Contacts app for Nextcloud easily syncs contacts from various devices with your Nextcloud and allows editing. Prior to 5.5.4, 6.0.6, and 7.2.5, a malicious user was able to modify their organisation and title field to load additional CSS files. Javascript and other options were correctly blocked by the content security policy of the Nextcloud Server code. This vulnerability is fixed in 5.5.4, 6.0.6, and 7.2.5.
How severe is CVE-2025-66554?: CVE-2025-66554 has a CVSS 3.x base score of 3.5, rated low severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2025-66554 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (11th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-66554?: CVE-2025-66554 affects Nextcloud Contacts. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-66554?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-66554 have an EU (EUVD) identifier?: Yes. CVE-2025-66554 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201461.
When was CVE-2025-66554 published?: CVE-2025-66554 was published on 2025-12-05 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:nextcloud:contacts:*:*:*:*:*:*:*:*

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