Critical severity · published Sep 7, 2021
CVE-2021-32802
Nextcloud server is an open source, self hosted personal cloud
9.8
CVSS
2.6%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)2.6% · higher than 85% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NS
Nextcloud Server · Nextcloud
before 20.0.12; 21.0.0 before 21.0.4; 22.0.0 before 22.1.0 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-32802
CVE.org
https://www.cve.org/CVERecord?id=CVE-2021-32802
Vendor Advisory
https://docs.nextcloud.com/server/21/admin_manual/configuration_files/previews_configuration.html#disabling-previews
Mitigation
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-m682-v4g9-wrq7
Permissions Required
https://hackerone.com/reports/1261413
Third Party Advisory
https://security.gentoo.org/glsa/202208-17
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