Vulnerability in Zauberzeug Nicegui
CVE-2026-21874
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.006 (44.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 45th percentile — 44.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.006 · change: +0.000
Affected products
- Zauberzeug Nicegui — versions >= 2.10.0, < 3.5.0
Weakness classification (CWE)
References
- github.com/zauberzeug/nicegui/security/advisories/GHSA-mp55-g7pj-rvm2 (Exploit, Vendor Advisory)
- github.com/zauberzeug/nicegui/commit/6c52eb2c90c4b67387c025b29646b4bc1578eb83 (Patch)
- github.com/zauberzeug/nicegui/releases/tag/v3.5.0 (Release Notes)
Frequently asked questions
- What is CVE-2026-21874?
- CVE-2026-21874 is a medium-severity vulnerability in Zauberzeug Nicegui, classified under Missing Release of Resource after Effective Lifetime. CVSS score: 5.3/10. Published 2026-01-08.
- How severe is CVE-2026-21874?
- Medium severity. CVSS v3 base score is 5.3 out of 10.