CVE-2021-32657Network attack vector

Authenticated user-administration denial of service

Published Jun 1, 2021 · Updated Aug 3, 2024

Denial of service in Nextcloud Server before 19.0.11, 20.0.10, or 21.0.2 allows remote authenticated users to block user administration. Nextcloud has not published the request, code path, or resource-consumption operation that causes the administration page to fail. A valid user account and network access to the server are required, and the reported consequence is loss of the web-based user-management function.

CVSS severity4.3
Medium
EPSS probability1.82%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Nextcloud Server before 19.0.11, 20.0.10, or 21.0.2 allows remote authenticated users to block user administration. Nextcloud has not published the request, code path, or resource-consumption operation that causes the administration page to fail. A valid user account and network access to the server are required, and the reported consequence is loss of the web-based user-management function.

The record

CVE
CVE-2021-32657
Published
Jun 1, 2021
Updated
Aug 3, 2024
Vendor
Nextcloud GmbH
Product
Nextcloud Security Advisories
Classifications
CWE-400, T1499
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 1, 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

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Is a vulnerable build present?

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

  1. Affected versionversion=< 19.0.11
  2. Affected versionversion=>= 20.0.0, < 20.0.10
  3. Affected versionversion=>= 21.0.0, < 21.0.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Nextcloud GmbH · Nextcloud Security Advisoriesversion=< 19.0.11; version=>= 20.0.0, < 20.0.10; version=>= 21.0.0, < 21.0.2

Published CVSS scores

4.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
4.0NIST NVDAV:N/AC:L/Au:S/C:N/I:N/A:P

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499Endpoint Denial of Service

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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