CVE-2026-39844
Published:April 08, 2026
Updated:April 20, 2026
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.
Affected Packages
nicegui (CONDA):
Affected version(s) >=1.2.10 <3.10.0Fix Suggestion:
Update to version 3.10.0https://github.com/zauberzeug/nicegui.git (GITHUB):
Affected version(s) >=v0.1.1 <v3.10.0Fix Suggestion:
Update to version v3.10.0nicegui (PYTHON):
Affected version(s) >=0.1.0 <3.10.0Fix Suggestion:
Update to version 3.10.0nicegui (PYTHON):
Affected version(s) >=0.1.0 <3.10.0Fix Suggestion:
Update to version 3.10.0Additional Notes
The description of this vulnerability differs from MITRE.
Related Resources (5)
Do you need more information?
Contact UsCVSS v4
Base Score:
8.2
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
HIGH
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
5.9
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
Weakness Type (CWE)
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
EPSS
Base Score:
0.06
