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CVE-2026-21871

MEDIUM CVSS 3.1: 6.1 EPSS 0.02%
Updated Jan 15, 2026
Zauberzeug
Parameter Value
CVSS 6.1 (MEDIUM)
Affected Versions 2.13.0 — 3.5.0
Fixed In 3.5.0
Type CWE-79 (Cross-Site Scripting (XSS))
Vendor Zauberzeug
Public PoC No

NiceGUI is a Python-based UI framework. From versions 2.13.0 to 3.4.1, there is a XSS risk in NiceGUI when developers pass attacker-controlled strings into ui.navigate.history.push() or ui.navigate.history.replace(). These helpers are documented as History API wrappers for updating the browser URL without page reload.

However, if the URL argument is embedded into generated JavaScript without proper escaping, a crafted payload can break out of the intended string context and execute arbitrary JavaScript in the victim’s browser. Applications that do not pass untrusted input into ui.navigate.history.push/replace are not affected. This issue has been patched in version 3.5.0.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
Required
User action required

Impact Assessment

Confidentiality
Low
Partial data leak
Integrity
Low
Partial data modification
Availability
None
No disruption

CVSS Vector v3.1

Vulnerable Products 1

Configuration From (including) Up to (excluding)
Zauberzeug Nicegui
cpe:2.3:a:zauberzeug:nicegui:*:*:*:*:*:*:*:*
2.13.0 3.5.0