CVE-2021-39222
6.4 · MEDIUMNextcloud is an open-source, self-hosted productivity platform.
Overview
CVE-2021-39222 is a medium-severity vulnerability. It was published on November 15, 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 Talk application 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 Talk application is upgraded to patched versions 10.0.7, 10.1.4, 11.1.2, 11.2.0 or 12.0.0. As a workaround, use a browser that has support for Content-Security-Policy.
Remediation
Check the references section for vendor advisories, patches, and mitigation guidance. 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.
References
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Frequently asked questions
What is CVE-2021-39222?
CVE-2021-39222 is a medium-severity vulnerability. It was published on November 15, 2021 and has a CVSS 3.1 base score of 6.4 (MEDIUM).
How severe is CVE-2021-39222?
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-2021-39222?
Check the references section for vendor advisories, patches, and mitigation guidance. 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-2021-39222?
CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-39222 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.
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