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Fencer Intel
medium 6.3

CVE-2026-102598 json

Werkzeug safe_join() allows Windows special device names

published last mo. modified 25d ago also EUVD-2026-88980 , GHSA-g6x2-hccm-hh4m , PYSEC-2026-4312

cvss
6.3
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 31%
public exploits
0
none known

Summary

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.

Patch / fix

  • pypi werkzeug 3.1.9
  • palletsprojects werkzeug 3.1.9
  • python-Werkzeug openSUSE Tumbleweed 3.1.9-1.1

opensuse advisories openSUSE-SU-2026:11943-1

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-102598 updated cvss 5.3

werkzeug: werkzeug: Denial of Service via safe_join() Windows special device paths

  • Red Hat OpenShift AI (RHOAI) rhoai/odh-mlflow-rhel9
    affected: no fix available “Fix deferred”
  • Red Hat AI Inference Server 3.4 rhaii/vllm-cpu-rhel9 1791857301, rhaii/vllm-cuda-rhel9 1791857183
    fixed: vendor fix RHSA-2026:83112
  • Red Hat AI Inference Server 3.5 rhaii/vllm-cpu-rhel9 1791473614, rhaii/vllm-cuda-rhel9 1791473631, rhaii/vllm-gaudi-rhel9 1791427182
    fixed: vendor fix RHSA-2026:82415
  • Red Hat Enterprise Linux AI 3.4 rhelai3/bootc-cuda-rhel9 1792612985, rhelai3/bootc-aws-cuda-rhel9 1792680701, rhelai3/bootc-gcp-cuda-rhel9 1792680694, rhelai3/disk-image-cuda-rhel9 1792701796, rhelai3/bootc-azure-cuda-rhel9 1792680694
    fixed: vendor fix RHSA-2026:90440
  • Red Hat Enterprise Linux AI 3.5 rhelai3/bootc-cuda-rhel9 1793135861, rhelai3/bootc-aws-cuda-rhel9 1793194817, rhelai3/bootc-gcp-cuda-rhel9 1793194815, rhelai3/disk-image-cuda-rhel9 1793206758, rhelai3/bootc-azure-cuda-rhel9 1793194815
    fixed: vendor fix RHSA-2026:92452
  • Red Hat Enterprise Linux AI 3.4 rhelai3/bootc-rocm-rhel9 1792612921, rhelai3/bootc-azure-rocm-rhel9 1792680669 Red Hat Enterprise Linux AI 3.5 rhelai3/bootc-rocm-rhel9 1793135863, rhelai3/bootc-azure-rocm-rhel9 1793194834
    not affected: vulnerable code not present
  • Red Hat Hardened Images python-urllib3 2.8.0-1.hum1, python-sentry-sdk 2.48.0-6.1.hum1
    not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
last mo.

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 4.0 6.3 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
CNA 4.0 6.3 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

Affected packages

ecosystem package affected fixed in
pypi werkzeug
<3.1.9
3.1.9

Affected products

  • pallets werkzeug

Classification

Weakness
  • CWE-67 Improper Handling of Windows Device Names

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.