CVE-2023-39958: Nextcloud Server

Medium severity, CVSS 5.3. EPSS: 0.7% chance of exploitation in the next 30 days.

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 22.0.0 and prior to versions 22.2.10.13, 23.0.12.8, 24.0.12.5, 25.0.9, 26.0.4, and 27.0.1, missing protection allows an attacker to brute force the client secrets of configured OAuth2 clients. Nextcloud Server versions 25.0.9, 26.0.4, and 27.0.1 and Nextcloud Enterprise Server versions 22.2.10.13, 23.0.12.8, 24.0.12.5, 25.0.9, 26.0.4, and 27.0.1 contain a patch for this issue. No known workarounds are available.

Affected products

• Nextcloud Nextcloud Server: from 22.0.0, before 22.2.10.14 (fixed in 22.2.10.14); from 23.0.0, before 23.0.12.9 (fixed in 23.0.12.9); from 24.0.0, before 24.0.12.5 (fixed in 24.0.12.5); from 25.0.0, before 25.0.9 (fixed in 25.0.9); from 26.0.0, before 26.0.4 (fixed in 26.0.4); version 27.0.0 only

Published 2023-08-10. Last modified 2026-06-17.