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TI-2023-20855 Aliases CVE-2023-39962

Users can delete external storage mount points

Priority HIGH 67CWE-284Published · Updated

Key facts

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

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-284.

Summary

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 19.0.0 and prior to versions 19.0.13.10, 20.0.14.15, 21.0.9.13, 22.2.10.14, 23.0.12.8, 24.0.12.5, 25.0.9, 26.0.4, and 27.0.1, a malicious user could delete any personal or global external storage, making them inaccessible for everyone else as well. Nextcloud server versions 25.0.9, 26.0.4, and 27.0.1 and Nextcloud Enterprise Server versions 19.0.13.10, 20.0.14.15, 21.0.9.13, 22.2.10.14, 23.0.12.9, 24.0.12.5, 25.0.9, 26.0.4, and 27.0.1 contain a patch for this issue. As a workaround, disable app files_external. This also makes the external storage inaccessible but retains the configurations until a patched version has been deployed.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.01023 63rd percentileScored 2026-11-07
Fix Fixed security-advisories (nextcloud): 19.0.13.10, 20.0.14.15, 21.0.9.13 +6

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
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-advisories19.0.0 to before 19.0.13.10; 20.0.0 to before 20.0.14.15; 21.0.0 to before 21.0.9.13; 22.0.0 to before 22.2.10.14; 23.0.0 to before 23.0.12.9; 24.0.0 to before 24.0.12.5; 25.0.0 to before 25.0.9; 26.0.0 to before 26.0.4; 27.0.0 to before 27.0.119.0.13.10, 20.0.14.15, 21.0.9.13, 22.2.10.14, 23.0.12.9, 24.0.12.5, 25.0.9, 26.0.4, 27.0.1Patch availableCNA
  • security-advisories Vendornextcloud Affected 19.0.0 to before 19.0.13.10; 20.0.0 to before 20.0.14.15; 21.0.0 to before 21.0.9.13; 22.0.0 to before 22.2.10.14; 23.0.0 to before 23.0.12.9; 24.0.0 to before 24.0.12.5; 25.0.0 to before 25.0.9; 26.0.0 to before 26.0.4; 27.0.0 to before 27.0.1 Fixed in 19.0.13.10, 20.0.14.15, 21.0.9.13, 22.2.10.14, 23.0.12.9, 24.0.12.5, 25.0.9, 26.0.4, 27.0.1 Patch available CNA

CPE configurations NVD · 7

CPEVersionsRoleVendor
cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:enterprise:*:*:*19.0.0 to before 19.0.13.10; 20.0.0 to before 20.0.14.15; 21.0.0 to before 21.0.9.13; 22.0.0 to before 22.2.10.14; 23.0.0 to before 23.0.12.9; 24.0.0 to before 24.0.12.5Vulnerablenextcloud
cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:-:*:*:*25.0.0 to before 25.0.9Vulnerablenextcloud
cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:enterprise:*:*:*25.0.0 to before 25.0.9Vulnerablenextcloud
cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:-:*:*:*26.0.0 to before 26.0.4Vulnerablenextcloud
cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:enterprise:*:*:*26.0.0 to before 26.0.4Vulnerablenextcloud
cpe:2.3:a:nextcloud:nextcloud_server:27.0.0:*:*:*:-:*:*:*27.0.0Vulnerablenextcloud
cpe:2.3:a:nextcloud:nextcloud_server:27.0.0:*:*:*:enterprise:*:*:*27.0.0Vulnerablenextcloud
  • cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:enterprise:*:*:* Versions 19.0.0 to before 19.0.13.10; 20.0.0 to before 20.0.14.15; 21.0.0 to before 21.0.9.13; 22.0.0 to before 22.2.10.14; 23.0.0 to before 23.0.12.9; 24.0.0 to before 24.0.12.5 Vulnerable ·nextcloud
  • cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:-:*:*:* Versions 25.0.0 to before 25.0.9 Vulnerable ·nextcloud
  • cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:enterprise:*:*:* Versions 25.0.0 to before 25.0.9 Vulnerable ·nextcloud
  • cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:-:*:*:* Versions 26.0.0 to before 26.0.4 Vulnerable ·nextcloud
  • cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:enterprise:*:*:* Versions 26.0.0 to before 26.0.4 Vulnerable ·nextcloud
  • cpe:2.3:a:nextcloud:nextcloud_server:27.0.0:*:*:*:-:*:*:* Versions 27.0.0 Vulnerable ·nextcloud
  • cpe:2.3:a:nextcloud:nextcloud_server:27.0.0:*:*:*:enterprise:*:*:* Versions 27.0.0 Vulnerable ·nextcloud

Remediation

  • Fix · CNA security-advisories (nextcloud) Fixed in 19.0.13.10, 20.0.14.15, 21.0.9.13, 22.2.10.14, 23.0.12.9, 24.0.12.5, 25.0.9, 26.0.4, 27.0.1

Timeline

  1. 2026-10-02 Threatist record created from CVE-2023-39962

References

Patch 1

Advisory 2

  • 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
  • TI-2022-08555 High memory usage in Nextcloud server 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