CVE-2025-21618 NiceGUI On Air authentication issue
Attackers can hijack user sessions by exploiting shared authentication state across browser instances, including incognito modes.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-21618?
CVE-2025-21618 is a high-severity authentication bypass vulnerability in zauberzeug nicegui, published on 6 Jan 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
NiceGUI is an easy-to-use, Python-based UI framework. Prior to 2.9.1, authenticating with NiceGUI logged in the user for all browsers, including browsers in incognito mode. This vulnerability is fixed in 2.9.1.
Weakness: CWE-287
Which versions are affected by CVE-2025-21618?
3 open source packages ship an affected version, including nicegui.
| Package | Affected | Fixed in |
|---|---|---|
nicegui PyPI | All versions | 2.9.1 |
nicegui PyPI | All versions | 2.9.1 |
nicegui PyPI | All versions | 2.9.1 |
How do I fix CVE-2025-21618?
Upgrade nicegui to 2.9.1 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2025-21618 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-21618 exists.
Sources
Also known as GHSA-v6jv-p6r8-j78w, PYSEC-2026-1705.