CVE-2023-39959: Nextcloud Server

Medium severity, CVSS 5.3. EPSS: 0.6% chance of exploitation in the next 30 days.

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 25.0.0 and prior to versions 25.0.9, 26.0.4, and 27.0.1, unauthenticated users could send a DAV request which reveals whether a calendar or an address book with the given identifier exists for the victim. Nextcloud Server versions 25.0.9, 26.0.4, and 27.0.1 and Nextcloud Enterprise Server versions 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 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.