What’s Vulnerable › Vulnerabilities

CVE-2025-66554: Nextcloud Contacts vulnerable to Stored XSS in contacts app via organisation and title field

• Severity: medium (CVSS 5.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-12-05 · updated 2026-10-15
• Weakness: CWE-79

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.

Affected products

• Nextcloud Contacts: from 5.0.0 before 5.5.4; from 6.0.0 before 6.0.6; from 7.0.0 before 7.2.5 — fixed in 5.5.4, 6.0.6, 7.2.5

How to fix

Upgrade to a fixed version: Nextcloud Contacts 5.5.4, 6.0.6, 7.2.5. Check the vendor advisory for mitigations.

References

• https://github.com/nextcloud/contacts/commit/d954d098978dde1f121600e8b994e02f293c68b1
• https://github.com/nextcloud/contacts/pull/4619
• https://github.com/nextcloud/security-advisories/security/advisories/GHSA-9v78-cpfc-v6h2
• https://hackerone.com/reports/3293290

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