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TI-2021-18075 Aliases CVE-2021-41239

User enumeration setting not respected in Nextcloud server

Priority LOW 33CWE-200Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Information disclosure, Security bypass
Confidentiality · integrity · availability
Low · None · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-200 and CWE-862.

Summary

Nextcloud server is a self hosted system designed to provide cloud style services. In affected versions the User Status API did not consider the user enumeration settings by the administrator. This allowed a user to enumerate other users on the instance, even when user listings where disabled. It is recommended that the Nextcloud Server is upgraded to 20.0.14, 21.0.6 or 22.2.1. There are no known workarounds.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.01248 69th percentileScored 2026-11-07
Fix Fixed security-advisories (nextcloud): 20.0.14, 21.0.6, 22.2.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
nextcloudsecurity-advisoriesbefore 20.0.14; 21.0.0 to before 21.0.6; 22.2.0 to before 22.2.120.0.14, 21.0.6, 22.2.1Patch availableCNA
  • security-advisories Vendornextcloud Affected before 20.0.14; 21.0.0 to before 21.0.6; 22.2.0 to before 22.2.1 Fixed in 20.0.14, 21.0.6, 22.2.1 Patch available CNA

CPE configurations NVD · 2

CPEVersionsRoleVendor
cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:*:*:*:*before 20.0.14; 21.0.0 to before 21.0.6Vulnerablenextcloud
cpe:2.3:a:nextcloud:nextcloud_server:22.2.0:*:*:*:*:*:*:*22.2.0Vulnerablenextcloud
  • cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:*:*:*:* Versions before 20.0.14; 21.0.0 to before 21.0.6 Vulnerable ·nextcloud
  • cpe:2.3:a:nextcloud:nextcloud_server:22.2.0:*:*:*:*:*:*:* Versions 22.2.0 Vulnerable ·nextcloud

Remediation

  • Fix · CNA security-advisories (nextcloud) Fixed in 20.0.14, 21.0.6, 22.2.1

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-41239

References

Patch 2

Advisory 2

  • TI-2023-20855 Users can delete external storage mount points CVSS 3.1HIGH 7.7
  • TI-2023-11091 Nextcloud download permissions can be changed by resharer CVSS 3.1HIGH 7.5
  • TI-2023-10624 Nextcloud Server vulnerable to SSRF via filter bypass due to lax checking on IPs CVSS 3.1MEDIUM 5.3
  • TI-2025-37238 Cross-site scripting in Nextcloud CVSS 3.1MEDIUM 6.4
  • TI-2023-11086 nextcloud vulnerable to Uncontrolled Resource Consumption CVSS 3.1MEDIUM 6.5
  • TI-2022-18738 Exception logging in Sharepoint app reveals clear-text connection details CVSS 3.1MEDIUM 6.5
See all 188 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences