CVE-2025-66548: Nextcloud Deck

Medium severity, CVSS 5.5. EPSS: 0.2% chance of exploitation in the next 30 days.

Nextcloud Deck is a kanban style organization tool aimed at personal planning and project organization for teams integrated with Nextcloud. Prior to 1.12.7, 1.14.4, and 1.15.1, file extension can be spoofed by using RTLO characters, tricking users into download files with a different extension than what is displayed. This vulnerability is fixed in 1.12.7, 1.14.4, and 1.15.1.

Affected products

• Nextcloud Deck: before 1.12.7 (fixed in 1.12.7); from 1.14.0, before 1.14.4 (fixed in 1.14.4); from 1.15.0, before 1.15.1 (fixed in 1.15.1)

Published 2025-12-05. Last modified 2026-06-17.