NiceGUI is a Python-based UI framework. The ui.markdown() component uses the markdown2 library to convert markdown content to HTML, which is then rendered via innerHTML. By default, markdown2 allows raw HTML to pass through unchanged. This means that if an application renders user-controlled content through ui.markdown(), an attacker can inject malicious HTML containing JavaScript event handlers. Unlike other NiceGUI components that render HTML (ui.html(), ui.chat_message(), ui.interactive_image()), the ui.markdown() component does not provide or require a sanitize parameter, leaving applications vulnerable to XSS attacks. This vulnerability is fixed in 3.7.0.
Advisories
Source ID Title
Github GHSA Github GHSA GHSA-v82v-c5x8-w282 NiceGUI's XSS vulnerability in ui.markdown() allows arbitrary JavaScript execution through unsanitized HTML content
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Mon, 09 Feb 2026 16:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 09 Feb 2026 11:00:00 +0000

Type Values Removed Values Added
First Time appeared Zauberzeug
Zauberzeug nicegui
Vendors & Products Zauberzeug
Zauberzeug nicegui

Fri, 06 Feb 2026 21:30:00 +0000

Type Values Removed Values Added
Description NiceGUI is a Python-based UI framework. The ui.markdown() component uses the markdown2 library to convert markdown content to HTML, which is then rendered via innerHTML. By default, markdown2 allows raw HTML to pass through unchanged. This means that if an application renders user-controlled content through ui.markdown(), an attacker can inject malicious HTML containing JavaScript event handlers. Unlike other NiceGUI components that render HTML (ui.html(), ui.chat_message(), ui.interactive_image()), the ui.markdown() component does not provide or require a sanitize parameter, leaving applications vulnerable to XSS attacks. This vulnerability is fixed in 3.7.0.
Title NiceGUI's XSS vulnerability in ui.markdown() allows arbitrary JavaScript execution through unsanitized HTML content
Weaknesses CWE-79
References
Metrics cvssV3_1

{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-02-09T15:27:15.351Z

Reserved: 2026-02-02T18:21:42.487Z

Link: CVE-2026-25516

cve-icon Vulnrichment

Updated: 2026-02-09T15:19:21.745Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-02-06T22:16:11.300

Modified: 2026-02-09T16:08:55.263

Link: CVE-2026-25516

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-02-09T10:49:50Z

Weaknesses