CVE-2021-32802Network attack vector

Server resource access via unsafe preview processing

Published Sep 7, 2021 · Updated Aug 3, 2024

Unsafe preview processing in Nextcloud Server before 20.0.12, 21.0.4, or 22.1.0 allows remote attackers to access server resources. The preview subsystem passes user-supplied image files to an unnamed third-party rendering library that is unsafe for untrusted content. Exposure requires enabled previews and a susceptible library and configuration; consequences include SSRF, file disclosure, code execution, or a service interrupt.

CVSS severity9.3
Critical
EPSS probability2.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unsafe preview processing in Nextcloud Server before 20.0.12, 21.0.4, or 22.1.0 allows remote attackers to access server resources. The preview subsystem passes user-supplied image files to an unnamed third-party rendering library that is unsafe for untrusted content. Exposure requires enabled previews and a susceptible library and configuration; consequences include SSRF, file disclosure, code execution, or a service interrupt.

The record

CVE
CVE-2021-32802
Published
Sep 7, 2021
Updated
Aug 3, 2024
Vendor
Nextcloud GmbH
Product
Nextcloud Security Advisories
Classifications
CWE-829, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 20.0.12
  2. Affected versionversion=>= 21.0.0, < 21.0.4
  3. Affected versionversion=>= 22.0.0, < 22.1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nextcloud GmbH · Nextcloud Security Advisoriesversion=< 20.0.12; version=>= 21.0.0, < 21.0.4; version=>= 22.0.0, < 22.1.0

Published CVSS scores

10.0NIST NVDAV:N/AC:L/Au:N/C:C/I:C/A:C
9.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:L
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-829Inclusion of Functionality from Untrusted Control Sphere
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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