What’s Vulnerable › Vulnerabilities

CVE-2021-39221: XSS in Contacts

• Severity: medium (CVSS 5.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-10-25 · updated 2026-06-17
• Weakness: CWE-79

Description

Nextcloud is an open-source, self-hosted productivity platform. The Nextcloud Contacts application prior to version 4.0.3 was vulnerable to a stored Cross-Site Scripting (XSS) vulnerability. For exploitation, a user would need to right-click on a malicious file and open the file in a new tab. Due the strict Content-Security-Policy shipped with Nextcloud, this issue is not exploitable on modern browsers supporting Content-Security-Policy. It is recommended that the Nextcloud Contacts application is upgraded to 4.0.3. As a workaround, one may use a browser that has support for Content-Security-Policy.

Affected products

• Nextcloud Contacts: before 4.0.3 — fixed in 4.0.3

How to fix

Upgrade to a fixed version: Nextcloud Contacts 4.0.3. Check the vendor advisory for mitigations.

References

• https://github.com/nextcloud/contacts/pull/2407
• https://github.com/nextcloud/security-advisories/security/advisories/GHSA-j6cx-mxqf-f9vc
• https://github.com/nextcloud/contacts/pull/2407
• https://github.com/nextcloud/security-advisories/security/advisories/GHSA-j6cx-mxqf-f9vc

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