TI-2023-17989 Aliases CVE-2023-35927

Nextcloud system addressbooks can be modified by malicious trusted server

LOW 37CWE-284Published 2023-06-23 · Updated 2024-11-07

Key facts

Attack vector: Network
Privileges required: Low
User interaction: None
Attack complexity: Low
Impact type: Security bypass
Confidentiality · integrity · availability: None · High · High
Fix status: No fix listed

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

Summary

NextCloud Server and NextCloud Enterprise Server provide file storage for Nextcloud, a self-hosted productivity platform. In NextCloud Server versions 25.0.0 until 25.0.7 and 26.0.0 until 26.0.2 and Nextcloud Enterprise Server versions 21.0.0 until 21.0.9.12, 22.0.0 until 22.2.10.12, 23.0.0 until 23.0.12.7, 24.0.0 until 24.0.12.2, 25.0.0 until 25.0.7, and 26.0.0 until 26.0.2, when two server are registered as trusted servers for each other and successfully exchanged the share secrets, the malicious server could modify or delete VCards in the system addressbook on the origin server. This would impact the available and shown information in certain places, such as the user search and avatar menu. If a manipulated user modifies their own data in the personal settings the entry is fixed again. Nextcloud Server n 25.0.7 and 26.0.2 and Nextcloud Enterprise Server 21.0.9.12, 22.2.10.12, 23.0.12.7, 24.0.12.2, 25.0.7, and 26.0.2 contain a patch for this issue. A workaround is available. Remove all trusted servers in the "Administration" > "Sharing" settings `…/index.php/settings/admin/sharing`. Afterwards, trigger a recreation of the local system addressbook with the following `occ dav:sync-system-addressbook`.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00805 56th percentileScored 2026-11-07

Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
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

Vendor	Product	Affected versions	Fixed in	Status	Source
nextcloud	security-advisories	Nextcloud Server >= 25.0.0, < 25.0.7; Nextcloud Server >= 26.0.0, < 26.0.2; Nextcloud Enterprise Server >= 25.0.0, < 25.0.7; Nextcloud Enterprise Server >= 26.0.0, < 26.0.2; Nextcloud Enterprise Server >= 21.0.0, < 21.0.9.12; Nextcloud Enterprise Server >= 22.0.0, < 22.2.10.12; Nextcloud Enterprise Server >= 23.0.0, < 23.0.12.7; Nextcloud Enterprise Server >= 24.0.0, < 24.0.12.2	—	No fix listed	CNA

security-advisories Vendornextcloud Affected Nextcloud Server >= 25.0.0, < 25.0.7; Nextcloud Server >= 26.0.0, < 26.0.2; Nextcloud Enterprise Server >= 25.0.0, < 25.0.7; Nextcloud Enterprise Server >= 26.0.0, < 26.0.2; Nextcloud Enterprise Server >= 21.0.0, < 21.0.9.12; Nextcloud Enterprise Server >= 22.0.0, < 22.2.10.12; Nextcloud Enterprise Server >= 23.0.0, < 23.0.12.7; Nextcloud Enterprise Server >= 24.0.0, < 24.0.12.2 Fixed in — No fix listed CNA

CPE configurations NVD · 5

CPE	Versions	Role	Vendor
cpe:2.3:a:nextcloud:nextcloud_server:::::enterprise:::*	16.0.0 to before 19.0.13.9; 20.0.0 to before 20.0.14.14; 21.0.0 to before 21.0.9.12; 22.0.0 to before 22.2.10.12; 23.0.0 to before 23.0.12.7; 24.0.0 to before 24.0.12.2	Vulnerable	nextcloud
cpe:2.3:a:nextcloud:nextcloud_server:::::-:::*	25.0.0 to before 25.0.7	Vulnerable	nextcloud
cpe:2.3:a:nextcloud:nextcloud_server:::::enterprise:::*	25.0.0 to before 25.0.7	Vulnerable	nextcloud
cpe:2.3:a:nextcloud:nextcloud_server:::::-:::*	26.0.0 to before 26.0.2	Vulnerable	nextcloud
cpe:2.3:a:nextcloud:nextcloud_server:::::enterprise:::*	26.0.0 to before 26.0.2	Vulnerable	nextcloud

cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:enterprise:*:*:* Versions 16.0.0 to before 19.0.13.9; 20.0.0 to before 20.0.14.14; 21.0.0 to before 21.0.9.12; 22.0.0 to before 22.2.10.12; 23.0.0 to before 23.0.12.7; 24.0.0 to before 24.0.12.2 Vulnerable ·nextcloud
cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:-:*:*:* Versions 25.0.0 to before 25.0.7 Vulnerable ·nextcloud
cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:enterprise:*:*:* Versions 25.0.0 to before 25.0.7 Vulnerable ·nextcloud
cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:-:*:*:* Versions 26.0.0 to before 26.0.2 Vulnerable ·nextcloud
cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:enterprise:*:*:* Versions 26.0.0 to before 26.0.2 Vulnerable ·nextcloud

Remediation

No fixed version listed by the sources yet.

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product

Red Hat

Timeline

2026-10-02 Threatist record created from CVE-2023-35927

References

Advisory 1

https://github.com/nextcloud/security-advisories/security/advisories/GHSA-h7f7-535f-7q87

Other 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