CVE-2026-39844 Details
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.
A path traversal vulnerability has been identified in NiceGUI, a Python-based UI framework, in versions prior to 3.10.0. The issue arises in the file upload feature, where filename sanitization can be bypassed on Windows systems. The vulnerability allows for arbitrary file writing by exploiting the way file paths are constructed using backslashes, which are interpreted as directory separators on Windows. This issue does not affect Linux or macOS, as those operating systems treat backslashes as literal characters in filenames.
Users can upgrade to NiceGUI version 3.10.0 or later, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Apr 9, 2026References to Advisories, Solutions, and Tools
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Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-22 | Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| zauberzeug nicegui | < 3.10.0 |
CPE
Remediation
| |
| microsoft windows | All versions |
CPE
Remediation
| |
Change History
5 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 24, 2026 | CVE Translated | [email protected] |
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Apr 15, 2026 | Initial Analysis | [email protected] |
| Apr 8, 2026 | New CVE Received | [email protected] |