CVE-2026-39844
Low
No strong exploitation signal.
CVSS base
5.9
MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS — probability of exploitation (30 days)
0.4%
31.0th percentile
CISA KEV
Not listed
Weakness / dates
CWE-22
Published 2026-04-08 · modified 2026-07-24
CVSS breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
| Attack Vector | N | Network |
| Attack Complexity | H | High |
| Privileges Required | N | None |
| User Interaction | N | None |
| Scope | U | Unchanged |
| Confidentiality | N | None |
| Integrity | H | High |
| Availability | N | None |
Timeline
- 2026-04-08 — Published (NVD)
- 2026-07-24 — Last modified (NVD)
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.