CVE-2026-102598

Updated on 29 Sep 2026

Severity

6.3 Medium severity

Details

CVSS score
6.3
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Overview

About vulnerability

Werkzeug’s safe_join function allows Windows device names as filenames when they have an empty ADS marker on NTFS.

This was previously reported as https://github.com/pallets/werkzeug/security/advisories/GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact Windows allows special device names with an empty ADS marker, such as NUL:.

send_from_directory uses safe_join to safely serve files at user-specified paths under a directory. If the application is running on Windows and NTFS, and the requested path ends with a special device name, the file will be opened successfully, but reading will hang indefinitely.

Details

Affected product:
Flask , Werkzeug , dash , mlflow , tensorboard , tensorflow
Affected packages:
werkzeug @ 1.0.1 (+15 more)

Fixes