What is CVE-2026-21872?

CVE-2026-21872 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-2026-21872?

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

XSS in Zauberzeug Nicegui

CVE-2026-21872

NiceGUI is a Python-based UI framework. From versions 2.22.0 to 3.4.1, an unsafe implementation in the click event listener used by ui.sub_pages, combined with attacker-controlled link rendering on the page, causes XSS when the user active…

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.002 (14.9th 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 >= 2.22.0, < 3.5.0

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)
security-advisories@github.com (x_refsource_MISC, Release Notes)

Frequently asked questions

What is CVE-2026-21872?: CVE-2026-21872 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-2026-21872?: Medium severity. CVSS v3 base score is 6.1 out of 10.