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CVE-2025-66469

MEDIUMCVSS 6.1/10EPSS 0.22%

Last modified

CVE-2025-66469 is a medium-severity vulnerability rated 6.1/10 on the CVSS scale. 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. EPSS estimates a 0.22% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
6.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS Probability
0.22%

12.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
ZauberzeugNicegui< 3.4.0

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2025-66469?
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.
How severe is CVE-2025-66469?
CVE-2025-66469 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 0.22% probability of exploitation in the next 30 days.
How do I fix CVE-2025-66469?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2025-66469?

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Source: NVD / NIST