CVE-2026-21871

MEDIUM

6.1

Description

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.

CVE Details

CVSS v3.1 Score6.1

SeverityMEDIUM

CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Attack VectorNETWORK

ComplexityLOW

Privileges RequiredNONE

User InteractionREQUIRED

Published1/8/2026

Last Modified1/15/2026

Sourcenvd

Honeypot Sightings0

Affected Products

zauberzeug:nicegui

Weaknesses (CWE)

CWE-79

References

https://github.com/zauberzeug/nicegui/releases/tag/v3.5.0(security-advisories@github.com)

https://github.com/zauberzeug/nicegui/security/advisories/GHSA-7grm-h62g-5m97(security-advisories@github.com)

IOC Correlations

No correlations recorded

This product uses data from the NVD API but is not endorsed or certified by the NVD.