ChangeIntel IT change radar

Public mode

No access to your tenant or devices. Every item links to its source. What this means

CVE-2026-102598

Werkzeug safe_join() allows Windows special device names

CVSS 4.0 6.3 MEDIUMCheck source for fixed versionsKEV status unknown

Original advisory

Historical advisory recorded 23 Oct 2026 15:48:27 UTC. Read the latest advisory.

cve-program · CVE-2026-102598

Published

Werkzeug is a comprehensive WSGI web application library. Prior to 3.1.9, the safe_join function used by send_from_directory can allow a NUL: special-device path because safe_join checks the Windows device name without first removing an empty NTFS ADS marker. The trigger is that an application runs on Windows with NTFS and serves a user-specified path ending in a special device name such as NUL:. The attack mechanism is that a requested path ends in a Windows special device name with an empty ADS marker. The impact is that the special device opens successfully and the file read hangs indefinitely. This issue is fixed in version 3.1.9.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-102598

Published

werkzeug

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "pallets",
                    "product": "werkzeug",
                    "versions": [
                        {
                            "version": "< 3.1.9",
                            "status": "affected"
                        }
                    ]
                }

Original source record · Cite this exact observation · Complete original publisher JSON