PT-2026-2112 · Nicegui · Nicegui

Evnchn · Published 2026-01-08 · Updated 2026-01-08 · CVE-2026-21873

Positive Technologies (AI Summary)

CVSS v3.1

7.2

High

Base vector

AV:N/AC:L/PR:N/UI:N/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. An unsafe implementation in the pushstate event listener used by ui.sub pages allows an attacker to manipulate the fragment identifier of the URL, even from a different site, using an iframe. This manipulation is possible due to a flaw in how the framework handles URL fragment changes within sub-pages. The pushstate event listener is the component responsible for managing the browser's history state, and its improper implementation allows for cross-site manipulation.

Recommendations Upgrade to NiceGUI version 3.5.0 or later to resolve this issue.

Exploit

Fix

XSS

Weakness Enumeration

CWE-79

Related Identifiers

CVE-2026-21873

GHSA-MHPG-C27V-6MXR

Affected Products

Nicegui

References · 9

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/21xxx/CVE-2026-21873.json · Exploit
• https://github.com/zauberzeug/nicegui/security/advisories/GHSA-mhpg-c27v-6mxr · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-21873 · Security Note
• https://osv.dev/vulnerability/CVE-2026-21873 · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-mhpg-c27v-6mxr · Vendor Advisory
• https://github.com/zauberzeug/nicegui · Note
• https://github.com/zauberzeug/nicegui/releases/tag/v3.5.0 · Note
• https://t.me/CVEtracker/41709 · Telegram Post
• https://twitter.com/CVEnew/status/2009208593829241222 · Twitter Post