CVE-2026-39844
Medium
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.
SeverityMedium
CVSS5.9
Exploit probability—
ProductZauberzeug Nicegui
PublishedApr 8, 2026
First seenApr 8, 2026
Weakness typeCWE-22Path traversal
How to fix
Update
- zauberzeug nicegui3.10.0 or later
- nicegui3.10.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| zauberzeug nicegui | v < 3.10.0 | 3.10.0 |
| niceguiPyPI | v < 3.10.0 | 3.10.0 |
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