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.
Published: 2026-04-08
Score: 5.9 Medium
EPSS: < 1% Very Low
KEV: No
Impact: Unrestricted File Write on Windows
Action: Patch Now
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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-w8wv-vfpc-hw2w NiceGUI: Upload filename sanitization bypass via backslashes allows path traversal on Windows
History

Wed, 15 Apr 2026 19:15:00 +0000

Type Values Removed Values Added
First Time appeared Microsoft
Microsoft windows
CPEs cpe:2.3:a:zauberzeug:nicegui:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:*
Vendors & Products Microsoft
Microsoft windows

Thu, 09 Apr 2026 17:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 09 Apr 2026 08:30:00 +0000

Type Values Removed Values Added
First Time appeared Zauberzeug
Zauberzeug nicegui
Vendors & Products Zauberzeug
Zauberzeug nicegui

Wed, 08 Apr 2026 20:30:00 +0000

Type Values Removed Values Added
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.
Title NiceGUI has a Path Traversal in NiceGUI Upload Filename on Windows via Backslash Bypass of PurePosixPath Sanitization
Weaknesses CWE-22
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N'}


Subscriptions

Microsoft Windows
Zauberzeug Nicegui
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-04-09T16:17:11.748Z

Reserved: 2026-04-07T19:13:20.377Z

Link: CVE-2026-39844

cve-icon Vulnrichment

Updated: 2026-04-09T14:55:51.231Z

cve-icon NVD

Status : Analyzed

Published: 2026-04-08T21:16:59.883

Modified: 2026-04-15T19:08:44.330

Link: CVE-2026-39844

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-04-09T08:27:25Z

Weaknesses