CVE-2026-102598

MEDIUM

6.3

CVSS v4

Description

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.

CWE-67

How to fix

Remediation Available

werkzeugPyPI (Python)

Fixed in:3.1.9GHSA-g6x2-hccm-hh4m

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v4 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

Impact

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

Exploit Intelligence

0.37%probability of exploitation in 30 days

31stpercentile

Low risk: more likely to be exploited than 31% of all known CVEs.

References

Other references4

Related Vulnerabilities

Other CWE-67 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-51745	Critical	10.0	0.8%	-	Fix
CVE-2026-27199	Medium	5.3	0.6%	-	Fix
CVE-2025-66221	Medium	5.3	0.5%	-	Fix
CVE-2026-21860	Medium	5.3	0.5%	-	Fix
CVE-2024-35197	Medium	5.4	0.4%	-	Fix
CVE-2026-17545	Medium	7.5	0.4%	-	Fix

Common questions

How do I fix CVE-2026-102598?

Upgrade werkzeug to 3.1.9 or later.

Is CVE-2026-102598 being actively exploited?

Not that we know of. CVE-2026-102598 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.37% is the estimated probability that it will be exploited in the next 30 days. That is higher than 31% of all scored CVEs.

How severe is CVE-2026-102598?

CVE-2026-102598 has a CVSS v4 base score of 6.3, rated moderate. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-102598 affect?

Published advisories record a fix for werkzeug (PyPI (Python)). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-30.