CVE-2021-39221
6.4 · MEDIUMOverview
CVE-2021-39221 is a medium-severity vulnerability affecting nextcloud contacts. It was published on October 25, 2021 and has a CVSS 3.1 base score of 6.4 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 6.4, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.
Technical 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.
Remediation
Check the references section for vendor advisories and patches from nextcloud. Update contacts to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| nextcloud | contacts | >= 0, < 4.0.3 | Affected |
Frequently Asked Questions
What is CVE-2021-39221?
CVE-2021-39221 is a medium-severity vulnerability affecting nextcloud contacts. It was published on October 25, 2021 and has a CVSS 3.1 base score of 6.4 (MEDIUM).
How severe is CVE-2021-39221?
This vulnerability has a CVSS 3.1 base score of 6.4, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.
How do I fix or remediate CVE-2021-39221?
Check the references section for vendor advisories and patches from nextcloud. Update contacts to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-39221?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-39221 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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