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CVE-2026-21873 Details

Description

NiceGUI is a Python-based UI framework. From versions 2.22.0 to 3.4.1, an unsafe implementation in the pushstate event listener used by ui.sub_pages allows an attacker to manipulate the fragment identifier of the URL, which they can do despite being cross-site, using an iframe. This issue has been patched in version 3.5.0.

Metrics

CVSS 3.x Severity and Vector Strings:

NIST: [email protected]CVSS-B:6.1 MEDIUMVector:CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CNA: [email protected]CVSS-B:7.2 HIGHVector:CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://github.com/zauberzeug/nicegui/releases/tag/v3.5.0	[email protected]	Release Notes
https://github.com/zauberzeug/nicegui/security/advisories/GHSA-mhpg-c27v-6mxr	[email protected]	ExploitVendor Advisory

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-79	Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')	[email protected]

Affected Products

Product	Versions
zauberzeug nicegui	>= 2.22.0, < 3.5.0
CPE cpe:2.3:a:zauberzeug:nicegui:::::::: Remediation No remediation found in references.

Change History

4 change records found show changes

Date	Action	Recorded By
Jun 17, 2026	CVE Modified	[email protected]
Jun 17, 2026	CVE Modified	CISA-ADP
Jan 15, 2026	Initial Analysis	[email protected]
Jan 8, 2026	New CVE Received	[email protected]