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CVE

CVE-2021-32802

Nextcloud server is an open source, self hosted personal cloud. Nextcloud supports rendering image previews for user pro

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.

CRITICAL · CVSS 9.3 EPSS 0.02254
Schedule remediation
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-829Inclusion of Functionality from Untrusted Control Sphere
CWE-829Inclusion of Functionality from Untrusted Control Sphere
▤

Affected Products & Versions

3
nextcloud server< 20.0.12
nextcloud server>= 21.0.0 and < 21.0.4
nextcloud server>= 22.0.0 and < 22.1.0
▣

Scoring & Timeline

9.3
CRITICAL · CVSS v3.1 · security-advisories@github.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD07 Sep 2021 · 10:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:L
⚑

Vendor Advisories

5
suse-csafopenSUSE-SU-2021:1275-1
suse-csafopenSUSE-SU-2021:1252-1
suse-csafopenSUSE-SU-2021:1253-1
suse-csafopenSUSE-SU-2021:1255-1
suse-csafopenSUSE-SU-2021:1250-1
🔗

References & Sources

4
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://docs.nextcloud.com/server/21/admin_manual/configuration_files/previews_configuration.html#disabling-previewsVendor Advisory
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-m682-v4g9-wrq7MitigationThird Party Advisory
https://hackerone.com/reports/1261413Permissions RequiredThird Party Advisory
https://security.gentoo.org/glsa/202208-17Third Party Advisory
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