What is the CVSS score of CVE-2026-42836?

CVE-2026-42836 has a CVSS 3.1 base score of 7.0 (High). CVSS vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

Which versions of Windows Function Discovery are affected by CVE-2026-42836?

Windows Function Discovery Service (fdwsd.dll) contains a local privilege escalation vulnerability allowing authenticated local users to gain administrative access through a race condition (CVSS…. A patch is available.

How to fix or mitigate CVE-2026-42836?

Within 24 hours: inventory Windows systems running fdwsd.dll and assess operational necessity of Function Discovery Service. Within 7 days: disable fdwsd.dll on systems where not operationally required; enforce principle of least privilege on local login access. Within 30 days: establish monitoring for suspicious fdwsd.dll execution and privilege escalation attempts; monitor Microsoft security advisories for patch availability; file support request with Microsoft for patch timeline.

Windows Function Discovery CVE-2026-42836

EUVD-2026-35590 HIGH

Race Condition (CWE-362)

2026-06-09 secure@microsoft.com

GHSA-cpvv-8639-q52m

Information Disclosure Race Condition Microsoft Windows 10 1607 Windows 10 1809 Windows 10 21h2 Windows 10 22h2 Windows 11 23h2 Windows 11 24h2 Windows 11 25h2 Windows 11 26h1 Windows Server 2012 Windows Server 2016 Windows Server 2019 Windows Server 2022 Windows Server 2025

7.0

CVSS 3.1 · Vendor: microsoft

Severity by source

Vendor (microsoft) PRIMARY

7.0 HIGH

AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Primary rating from Vendor (microsoft) · only source for this CVE.

CVSS VectorVendor: microsoft

Attack Vector

Local

Attack Complexity

High

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Patch available

Jun 09, 2026 - 19:03 EUVD

Analysis Generated

Jun 09, 2026 - 17:38 vuln.today

DescriptionCVE.org

Concurrent execution using shared resource with improper synchronization ('race condition') in Function Discovery Service (fdwsd.dll) allows an authorized attacker to elevate privileges locally.

AnalysisAI

Local privilege escalation in the Windows Function Discovery Service (fdwsd.dll) allows an authorized low-privileged attacker on the host to win a race condition and obtain elevated privileges. Reported by Microsoft (secure@microsoft.com) and tracked under MSRC's update guide, the issue carries a CVSS 7.0 score driven by high impact across confidentiality, integrity, and availability, though the high attack complexity reflects the timing window required. No public exploit identified at time of analysis and the flaw is not currently listed in CISA KEV.

Technical ContextAI

Function Discovery (FD) is a Windows subsystem that abstracts the enumeration of devices and services (e.g., PnP-X, WSD, UPnP, SSDP) for applications such as Network Discovery, the device association framework, and Devices and Printers. fdwsd.dll specifically implements the Web Services on Devices (WSD) provider that handles discovery of networked peripherals like printers and scanners. The underlying weakness is CWE-362 (Concurrent Execution Using Shared Resource with Improper Synchronization, a.k.a. race condition), meaning two or more threads in the FD service access a shared object - likely a discovery handle, device list entry, or callback structure - without proper locking, creating a Time-of-Check to Time-of-Use (TOCTOU) or use-after-free style window that the attacker can leverage to corrupt state and gain code execution at the privilege level of the host service (typically LocalService/SYSTEM). No CPE strings were provided in the input, but the MSRC advisory is the authoritative product/version source.

RemediationAI

Apply the Microsoft security update referenced in the MSRC update guide entry at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42836 for each affected Windows SKU and build; patch available per vendor advisory, but no exact fix KB or build number was included in the input data, so consult the advisory for the matching KB. As a temporary compensating control where patching must wait, disable Network Discovery on affected hosts (Control Panel → Network and Sharing Center → Advanced sharing settings → Turn off network discovery) or stop and disable the Function Discovery Provider Host (fdPHost) and Function Discovery Resource Publication (FDResPub) services - be aware this breaks discovery of WSD printers/scanners, UPnP devices, and Devices and Printers enumeration. On shared multi-user systems, tighten interactive logon rights so untrusted users cannot run code locally, since exploitation requires PR:L (an authenticated local user).