CVE-2026-39844NiceGUI has a Path Traversal in NiceGUI Upload Filename on Windows via Backslash Bypass of PurePosixPath Sanitization
- 5.9MediumCVSS base score
- 0.39%Exploitation in 30 daysEPSS · top 67% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By GitHub_M
- 1 day later
· 1 day later
Published
- 1 day later
· 1 day later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | Medium5.9 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N |
| NVDNVD · Analyzed | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
- EPSS (exploitation in 30 days)
- 0.39% · top 67% of all CVEs (15 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.9.
Affected products
- affected < 3.10.0
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- PyPIniceguiGHSA-w8wv-vfpc-hw2w (opens in a new tab)
References
References3
- https://github.com/zauberzeug/nicegui/security/advisories/GHSA-w8wv-vfpc-hw2w (opens in a new tab)x_refsource_CONFIRM
- https://github.com/zauberzeug/nicegui/commit/d38a702e3af2da5b0708f689be8d71413fc77056 (opens in a new tab)x_refsource_MISC
- https://github.com/zauberzeug/nicegui/releases/tag/v3.10.0 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-20610 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-w8wv-vfpc-hw2w (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-39844)Record last updated .