CVE-2026-39844
NiceGUI has a Path Traversal in NiceGUI Upload Filename on Windows via Backslash Bypass of PurePosixPath Sanitization
CVSS Score
5.9
EPSS Score
0.1%
EPSS Percentile
16th
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.
| CWE | CWE-22 |
| Vendor | zauberzeug |
| Product | nicegui |
| Published | Apr 8, 2026 |
| Last Updated | Apr 9, 2026 |
Stay Ahead of the Next One
Get instant alerts for zauberzeug nicegui
Be the first to know when new medium vulnerabilities affecting zauberzeug nicegui are published — delivered to Slack, Telegram or Discord.
Get Free Alerts →
Free · No credit card · 60 sec setup
CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None
Affected Versions
zauberzeug / nicegui
< 3.10.0