XSS Vulnerability in NiceGUI Python UI Framework
CVE-2026-25516

6.1MEDIUM

Key Information:

Vendor

Zauberzeug

Status
Nicegui
Vendor
CVE Published:
6 February 2026

What is CVE-2026-25516?

The NiceGUI framework, a Python-based UI solution, features a ui.markdown() component vulnerable to cross-site scripting (XSS) due to its reliance on the markdown2 library for converting markdown into HTML. This component does not sanitize user input, allowing attackers to inject malicious HTML and JavaScript event handlers into applications that render user-controlled content. Unlike other components in NiceGUI that offer sanitization, ui.markdown() exposes applications to serious security threats. Users are advised to update to version 3.7.0 or later to mitigate this risk.

Affected Version(s)

nicegui < 3.7.0

References

https://github.com/zauberzeug/nicegui/security/advisories...
x_refsource_CONFIRM
https://github.com/zauberzeug/nicegui/commit/f1f753357787...
x_refsource_MISC

CVSS V3.1

Score:
6.1
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
Low
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
Required
Scope:
Changed

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.