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Vulnerability record · CVE-2021-32802 · published 7 September 2021

CVE-2021-32802: Nextcloud server inclusion from untrusted sphere vulnerability

Nextcloud · Nextcloud Server

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`.

9.8 CVSS 3.1 Critical EPSS 2.6% · top 15.2% CWE-829 · Inclusion from untrusted sphere
9.8CVSS 3.1 base score, v2 10.0
2.6%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
8References
17 Jun 2026Last modified by NVD

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`.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://docs.nextcloud.com/server/21/admin_manual/configuration_files/previews_configuration.html#disabling-previews Vendor Advisory
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-m682-v4g9-wrq7 MitigationThird Party Advisory
https://hackerone.com/reports/1261413 Permissions RequiredThird Party Advisory
https://security.gentoo.org/glsa/202208-17 Third Party Advisory
https://docs.nextcloud.com/server/21/admin_manual/configuration_files/previews_configuration.html#disabling-previews Vendor Advisory
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-m682-v4g9-wrq7 MitigationThird Party Advisory
https://hackerone.com/reports/1261413 Permissions RequiredThird Party Advisory
https://security.gentoo.org/glsa/202208-17 Third Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-32802), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.