CVE-2021-41239Network attack vector

Account-name disclosure via ignored enumeration setting

Published Mar 8, 2022 · Updated Apr 23, 2025

Information disclosure in Nextcloud Server before 20.0.14, 21.0.0 through 21.0.5, and 22.2.0 allows remote attackers to enumerate users. The User Status API's last-statuses widget returns account names without applying the administrator's disabled user-enumeration setting. An unauthenticated network request is sufficient, and the disclosed account names enable reconnaissance but do not expose account contents.

CVSS severity5.3
Medium
EPSS probability1.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Nextcloud Server before 20.0.14, 21.0.0 through 21.0.5, and 22.2.0 allows remote attackers to enumerate users. The User Status API's last-statuses widget returns account names without applying the administrator's disabled user-enumeration setting. An unauthenticated network request is sufficient, and the disclosed account names enable reconnaissance but do not expose account contents.

The record

CVE
CVE-2021-41239
Published
Mar 8, 2022
Updated
Apr 23, 2025
Vendor
Nextcloud GmbH
Product
Security Advisories
Classifications
CWE-200, T1087
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 8, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 23, 2025Record 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=< 20.0.14
  2. Affected versionversion=>= 21.0.0, < 21.0.6
  3. Affected versionversion=>= 22.2.0, < 22.2.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nextcloud GmbH · Security Advisoriesversion=< 20.0.14; version=>= 21.0.0, < 21.0.6; version=>= 22.2.0, < 22.2.1

Published CVSS scores

5.3GitHub_MCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

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-200Exposure of Sensitive Information to an Unauthorized Actor
T1087Account Discovery

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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