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CVE-2026-21871
Good to know:
Date: January 8, 2026
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.
Severity Score
Related Resources (5)
Severity Score
Weakness Type (CWE)
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-79Top Fix
Upgrade Version
Upgrade to version nicegui - 3.5.0;https://github.com/zauberzeug/nicegui.git - v3.5.0
CVSS v3.1
| Base Score: |
|
|---|---|
| Attack Vector (AV): | NETWORK |
| Attack Complexity (AC): | LOW |
| Privileges Required (PR): | NONE |
| User Interaction (UI): | REQUIRED |
| Scope (S): | CHANGED |
| Confidentiality (C): | LOW |
| Integrity (I): | LOW |
| Availability (A): | NONE |