VulnerabilityAnalyzed

CVE-2025-66469

Versions 3.3.1 and below are vulnerable to Reflected XSS through its ui.add_css, ui.add_scss, and ui.add_sass functions.

MEDIUM 6.1EPSS 0.27%

Does this matter?

Lower severity and a low EPSS score (0.27%). Track it; it rarely justifies an emergency change on its own.

Description

NiceGUI is a Python-based UI framework. Versions 3.3.1 and below are vulnerable to Reflected XSS through its ui.add_css, ui.add_scss, and ui.add_sass functions. The functions lack proper sanitization or encoding for the JavaScript context they generate. An attacker can break out of the intended <style> or <script> tags by injecting closing tags (e.g., </style> or </script>), allowing for the execution of arbitrary JavaScript. This issue is fixed in version 3.4.0.

CVSS 3.1: 6.1 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
EPSS: 0.27% probability · 20th percentile
CISA KEV: Not listed
Weakness: CWE-79
Affected: zauberzeug/nicegui
Source: security-advisories@github.com

References

https://github.com/zauberzeug/nicegui/commit/a8fd25b7d5e23afb1952d0f60a1940e18b5f1ca8Patch
https://github.com/zauberzeug/nicegui/security/advisories/GHSA-72qc-wxch-74mgExploit, Vendor Advisory
https://github.com/zauberzeug/nicegui/security/advisories/GHSA-72qc-wxch-74mgExploit, Vendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.