What is CVE-2026-21871?

CVE-2026-21871 is a medium-severity vulnerability in Zauberzeug Nicegui, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-01-08.

How severe is CVE-2026-21871?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Zauberzeug Nicegui

CVE-2026-21871

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 docu…

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.000 (5.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

Affected products

Zauberzeug Nicegui — versions >= 2.13.0, < 3.5.0

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

https://github.com/zauberzeug/nicegui/security/advisories/GHSA-7grm-h62g-5m97 (x_refsource_CONFIRM)
https://github.com/zauberzeug/nicegui/releases/tag/v3.5.0 (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-21871?: CVE-2026-21871 is a medium-severity vulnerability in Zauberzeug Nicegui, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-01-08.
How severe is CVE-2026-21871?: Medium severity. CVSS v3 base score is 6.1 out of 10.