HOME VULNERABILITIESCVE-2021-32802

CRITICAL

CVE-2021-32802

CWE-829Published: September 7, 2021· Updated: Jun 17, 2026

9.8

CVSS v3.1

Official 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`.

Technical Analysis

CVE-2021-32802 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

CVSS v3.1 Vector Breakdown

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges Req.None

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Affected Vendors & Products

nextcloud1 product(s)

nextcloud server

Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time

Offensive Security exploit database

GitHub PoC Search

Community PoC repositories

Rapid7 / Metasploit

Metasploit module search

Security advisories & exploits

Official NIST entry

CVE Program entry

External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://docs.nextcloud.com/server/21/admin_manual/configuration_files/previews_configuration.html#disabling-previews

ADVISORYhttps://github.com/nextcloud/security-advisories/security/advisories/GHSA-m682-v4g9-wrq7

ADVISORYhttps://hackerone.com/reports/1261413

ADVISORYhttps://security.gentoo.org/glsa/202208-17

ADVISORYhttps://docs.nextcloud.com/server/21/admin_manual/configuration_files/previews_configuration.html#disabling-previews

ADVISORYhttps://github.com/nextcloud/security-advisories/security/advisories/GHSA-m682-v4g9-wrq7

ADVISORYhttps://hackerone.com/reports/1261413

ADVISORYhttps://security.gentoo.org/glsa/202208-17

All References (8)

→

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-wrq7Mitigation · Third Party Advisory

→

https://hackerone.com/reports/1261413Permissions Required · Third Party Advisory

→

https://security.gentoo.org/glsa/202208-17Third Party Advisory

→

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-wrq7Mitigation · Third Party Advisory

→

https://hackerone.com/reports/1261413Permissions Required · Third Party Advisory

→

https://security.gentoo.org/glsa/202208-17Third Party Advisory

Quick Facts

CVE IDCVE-2021-32802

CVSS Score9.8 / 10

SeverityCRITICAL

WeaknessCWE-829

CISA KEVNo

Affected1 vendor(s)

PublishedSep 7, 2021

Related CVEs (CWE-829)

Recommended Actions

→Apply vendor patches immediately
→Monitor CVE-2021-32802 in threat intel feeds
→Review IDS/IPS signatures for exploitation attempts

Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.

← All Vulnerabilities·Search for CVE-2021-32802·NVD