CVE-2026-21874: Zauberzeug Nicegui

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

NiceGUI is a Python-based UI framework. From versions v2.10.0 to 3.4.1, an unauthenticated attacker can exhaust Redis connections by repeatedly opening and closing browser tabs on any NiceGUI application using Redis-backed storage. Connections are never released, leading to service degradation when Redis hits its connection limit. NiceGUI continues accepting new connections - errors are logged but the app stays up with broken storage functionality. This issue has been patched in version 3.5.0.

Affected products

• Zauberzeug Nicegui: from 2.10.0, before 3.5.0 (fixed in 3.5.0)

Published 2026-01-08. Last modified 2026-06-17.