CVE-2026-21874

NiceGUI has Redis connection leak via tab storage causes service degradation

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

zauberzeug · nicegui

CVSS v3.1 GITHUB

5.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS

0.55% chance of exploitation in the next 30 days, 45th percentile

Published

2026-01-08

Proof-of-concept exploits (1)

• advisories/GHSA-mp55-g7pj-rvm2

Security advisories

• zauberzeug/nicegui/security/advisories/GHSA-mp55-g7pj-rvm2
• zauberzeug/nicegui/commit/6c52eb2c90c4b67387c025b29646b4bc1578eb83

References

• CVE Record
• NVD entry