PT-2026-2111 · Nicegui · Nicegui

Evnchn + 1 · Published 2026-01-08 · Updated 2026-01-08 · CVE-2026-21872

Positive Technologies (AI Summary)

CVSS v3.1

6.1

Medium

Base vector

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

Name of the Vulnerable Software and Affected Versions NiceGUI versions 2.22.0 through 3.4.1

Description NiceGUI is a Python-based UI framework susceptible to a cross-site scripting (XSS) issue. The problem stems from an unsafe implementation within the click event listener used by ui.sub pages, coupled with the rendering of attacker-controlled links on the page. When a user clicks on such a link, XSS can occur. The issue involves the ui.sub pages function and the handling of links.

Recommendations Upgrade to NiceGUI version 3.5.0 or later.

Exploit

Fix

XSS

Weakness Enumeration

CWE-79

Related Identifiers

CVE-2026-21872

GHSA-M7J5-RQ9J-6JJ9

Affected Products

Nicegui

References · 9

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/21xxx/CVE-2026-21872.json · Exploit
• https://github.com/zauberzeug/nicegui/security/advisories/GHSA-m7j5-rq9j-6jj9 · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-m7j5-rq9j-6jj9 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2026-21872 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-21872 · Security Note
• https://github.com/zauberzeug/nicegui · Note
• https://github.com/zauberzeug/nicegui/releases/tag/v3.5.0 · Note
• https://twitter.com/CVEnew/status/2009208594714284227 · Twitter Post
• https://t.me/CVEtracker/41708 · Telegram Post