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CVE-2021-32802

9.3 · CRITICAL

Nextcloud server is an open source, self hosted personal cloud.

Published Sep 7, 2021CWE-829EPSS 2.60%

Overview

CVE-2021-32802 is a critical-severity vulnerability. It was published on September 7, 2021 and has a CVSS 3.1 base score of 9.3 (CRITICAL).

This vulnerability has a CVSS 3.1 base score of 9.3, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

Nextcloud server is an open source, self hosted personal cloud. Nextcloud supports rendering image previews for user provided file content. For some image types, the Nextcloud server was invoking a third-party library that wasn't suited for untrusted user-supplied content. There are several security concerns with passing user-generated content to this library, such as Server-Side-Request-Forgery, file disclosure or potentially executing code on the system. The risk depends on your system configuration and the installed library version. It is recommended that the Nextcloud Server is upgraded to 20.0.12, 21.0.4 or 22.1.0. These versions do not use this library anymore. As a workaround users may disable previews by setting `enable_previews` to `false` in `config.php`.

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

Refdocs.nextcloud.com/server/21/admin_manual/configuration_files/previews_configuration.html#disabling-previewsGitHubgithub.com/nextcloud/security-advisories/security/advisories/GHSA-m682-v4g9-wrq7Refhackerone.com/reports/1261413Refsecurity.gentoo.org/glsa/202208-17Refdocs.nextcloud.com/server/21/admin_manual/configuration_files/previews_configuration.html#disabling-previewsGitHubgithub.com/nextcloud/security-advisories/security/advisories/GHSA-m682-v4g9-wrq7Refhackerone.com/reports/1261413Refsecurity.gentoo.org/glsa/202208-17

How CyberStrike helps

Frequently asked questions

What is CVE-2021-32802?

CVE-2021-32802 is a critical-severity vulnerability. It was published on September 7, 2021 and has a CVSS 3.1 base score of 9.3 (CRITICAL).

How severe is CVE-2021-32802?

This vulnerability has a CVSS 3.1 base score of 9.3, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2021-32802?

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-2021-32802?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-32802 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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