What is CVE-2023-35927?

CVE-2023-35927 is a high-severity vulnerability in Nextcloud Server, classified under Improper Access Control. CVSS score: 7.6/10. Published 2023-06-23.

How severe is CVE-2023-35927?

High severity. CVSS v3 base score is 7.6 out of 10.

Vulnerability in Nextcloud Server

CVE-2023-35927

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`.

EPSS: 0.008 (53.1th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.6 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:H/A:L.

Affected products

Nextcloud Nextcloud_server
Nextcloud Security-advisories — versions 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

Weakness classification (CWE)

CWE-284 — Improper Access Control

References

security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
security-advisories@github.com (x_refsource_MISC, Issue Tracking)
security-advisories@github.com (Permissions Required, x_refsource_MISC)

Frequently asked questions

What is CVE-2023-35927?: CVE-2023-35927 is a high-severity vulnerability in Nextcloud Server, classified under Improper Access Control. CVSS score: 7.6/10. Published 2023-06-23.
How severe is CVE-2023-35927?: High severity. CVSS v3 base score is 7.6 out of 10.