CVE-2026-39844

Name: CVE-2026-39844
Creator: NVD / NIST
Published: 2026-04-08T21:16:59.883+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 0.37%

Last modified Jun 17, 2026

CVE-2026-39844 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. NiceGUI is a Python-based UI framework. Prior to 3.10.0, Since PurePosixPath only recognizes forward slashes (/) as path separators, an attacker can bypass this sanitization on Windows by using backslashes (\) in the upload filename. EPSS estimates a 0.37% chance of exploitation in the next 30 days.

Description

NiceGUI is a Python-based UI framework. Prior to 3.10.0, Since PurePosixPath only recognizes forward slashes (/) as path separators, an attacker can bypass this sanitization on Windows by using backslashes (\) in the upload filename. Applications that construct file paths using file.name (a pattern demonstrated in NiceGUI's bundled examples) are vulnerable to arbitrary file write on Windows. This vulnerability is fixed in 3.10.0.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

0.37%

28.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-22

Affected Software

Vendor	Product	Versions
Zauberzeug	Nicegui	< 3.10.0

References

Timeline

Published: Apr 8, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-39844?

How severe is CVE-2026-39844?

CVE-2026-39844 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.37% probability of exploitation in the next 30 days.

How do I fix CVE-2026-39844?

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-2026-39844?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST