Skip to main content

Windows MDM CVE-2026-83697

| EUVDEUVD-2026-99955 MEDIUM
Time-of-check Time-of-use (TOCTOU) Race Condition (CWE-367)
2026-10-13 secure@microsoft.com GHSA-wg4c-xqx3-f9ph
4.7
CVSS 3.1 · Vendor: microsoft
View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Obtain local low-privileged account
  2. Exploit
    Invoke Windows MDM operation
  3. Execution
    Race TOCTOU window between check and use
  4. Impact
    Tamper with managed resource integrity

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture TOCTOU prevention
Exploitation Conditions

Exploitation requires an attacker to already possess a local, authenticated low-privileged account (PR:L) on the target Windows system and to interact with the Modern Device Management (MDM) subsystem. The core limiting factor is the TOCTOU race condition (CWE-367): the attacker must win a narrow timing window between the component's validation of a resource and its use, which the high attack complexity (AC:H) reflects - success is non-deterministic and typically needs many attempts. There is no remote vector (AV:L) and no user-interaction requirement (UI:N). Impact is confined to integrity/tampering (I:H) with no confidentiality (C:N) or availability (A:N) effect. Affected builds span Windows 10 (1809/21H2/22H2), Windows 11 (23H2/24H2/25H2/26H1/26H2), and Windows Server 2019/2022/2025; systems patched to the fixed builds (e.g., 10.0.26100.33650 for Server 2025, 10.0.17763.9376 for 1809) are not exploitable.

Impact

This is a genuinely low-priority vulnerability despite a MEDIUM CVSS of 4.7. The CVSS vector (AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N) tells a consistent, limiting story: exploitation requires local access (AV:L), already-held privileges (PR:L), and a hard-to-win race window (AC:H), yielding only an integrity impact (I:H) with no confidentiality or availability loss. Every secondary signal agrees with this low-urgency picture: CISA's SSVC decision reports Exploitation=none, Automatable=no, and Technical Impact=partial, and there is no CISA KEV listing and no public exploit identified at time of analysis. No EPSS score was provided in the input, so exploitation probability cannot be quantified, but the TOCTOU/AC:H nature inherently resists reliable or automated weaponization. One cross-source inconsistency: the input Tags include 'Information Disclosure,' yet both the description ('perform tampering') and the CVSS metrics (C:N, I:H) indicate an integrity/tampering flaw, not disclosure - the tag appears mislabeled and should not drive triage. Net assessment: a real but minor local tampering issue, appropriate for routine patch-cycle remediation rather than emergency response.

Exploit ScenarioDerived

A local attacker who already holds a standard authenticated account on a Windows host repeatedly triggers an MDM operation while racing to swap a resource between the device management component's validation check and its subsequent use, winning a narrow timing window to tamper with managed state or policy data. No public exploit code has been identified, and the high attack complexity (AC:H) means success requires repeated attempts to hit the race condition rather than a single deterministic action.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.2% exploitation probability (EPSS)

Get an e-mail when this CVE is exploited, patched or re-scored. Free account.

Alert me

AnalysisAIv1 – Oct 14, 2026

Local tampering of Windows Modern Device Management (MDM) state is possible on affected Windows 10, Windows 11, and Windows Server builds, because a TOCTOU race condition (CWE-367) lets an attacker who already holds an authenticated low-privileged local account alter a resource in the window between its validation and its use. Exploitation is non-deterministic and typically requires many attempts (CVSS 4.7, AV:L/AC:H/PR:L/UI:N), there is no remote vector and no user-interaction requirement, and impact is confined to integrity (I:H) with no confidentiality or availability effect. Microsoft has shipped fixes and CISA's SSVC assessment records no observed exploitation and no automatable path, so this ranks as a genuinely low-priority issue; no public exploit code has been identified at time of analysis.

RemediationAI

Apply the Microsoft monthly cumulative update for the applicable Windows servicing branch; the EUVD ranges indicate fixed builds of 10.0.17763.9376 for Windows 10 1809 and Windows Server 2019, 10.0.19044.7807 for Windows 10 21H2/22H2, 10.0.22631.7652 for Windows 11 23H2, 10.0.20348.5761 for Windows Server 2022, 10.0.26100.33650 for Windows Server 2025, 10.0.26100.9711 for Windows 11 24H2, 10.0.26200.9711 for Windows 11 25H2, 10.0.28000.3231 for Windows 11 26H1, and 10.0.26300.9711 for Windows 11 26H2, with patch availability confirmed by the vendor advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83697. Because the flaw requires an existing authenticated low-privileged local account and high-complexity timing, there is no meaningful network-side workaround; the practical compensating controls are to reduce the local attacker population that can touch MDM-managed state (remove unnecessary local admin and standard-user accounts, restrict which users are permitted to enroll or manage devices, and limit interactive/RDP access to managed endpoints), accepting the operational trade-off of reduced self-service enrollment and heavier helpdesk load. Organizations that cannot patch immediately should raise monitoring for repeated local MDM-configuration or MDM policy-store write attempts in a short window, since the race typically requires many tries and produces distinctive retry patterns, but this is a detection rather than a prevention measure and should not be treated as equivalent to applying the update.

Affected VersionsENISA

Windows 11 Version 25H2 10.0.26200.0 <10.0.26200.9711
Windows 11 Version 26H2 10.0.26300.0 <10.0.26300.9711
Windows 10 Version 1809 10.0.17763.0 <10.0.17763.9376
Windows 10 Version 22H2 10.0.19045.0 <10.0.19044.7807
Windows 11 version 26H1 10.0.28000.0 <10.0.28000.3231
Windows 10 Version 21H2 10.0.19044.0 <10.0.19044.7807
Windows Server 2019 (Server Core installation) 10.0.17763.0 <10.0.17763.9376
Windows Server 2025 10.0.26100.0 <10.0.26100.33650
Windows Server 2025 (Server Core installation) 10.0.26100.0 <10.0.26100.33650
Windows 11 Version 24H2 10.0.26100.0 <10.0.26100.9711
Windows Server 2022 10.0.20348.0 <10.0.20348.5761
Windows Server 2019 10.0.17763.0 <10.0.17763.9376
Windows 11 Version 23H2 10.0.22631.0 <10.0.22631.7652

Affected Packages

euvd windows_10_version_1809 fix: 10.0.17763.9376
euvd windows_10_version_21h2 fix: 10.0.19044.7807
euvd windows_10_version_22h2 fix: 10.0.19044.7807
euvd windows_11_version_23h2 fix: 10.0.22631.7652
euvd windows_11_version_24h2 fix: 10.0.26100.9711
euvd windows_11_version_25h2 fix: 10.0.26200.9711
euvd windows_11_version_26h1 fix: 10.0.28000.3231
euvd windows_11_version_26h2 fix: 10.0.26300.9711
euvd windows_server_2019 fix: 10.0.17763.9376
euvd windows_server_2019_server_core_installation fix: 10.0.17763.9376
euvd windows_server_2022 fix: 10.0.20348.5761
euvd windows_server_2025 fix: 10.0.26100.33650
euvd windows_server_2025_server_core_installation fix: 10.0.26100.33650

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 13 packages in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The root cause class is CWE-367, time-of-check time-of-use, in which the MDM component validates a resource (for example an MDM-managed file, registry value, or policy object) and then operates on it in a separate step, leaving a narrow window in which the object can be swapped or modified after the check. The CVSS vector CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N tells the whole story: the attack surface is local only (AV:L), the attacker must already be authenticated with low privileges (PR:L) on the target, no victim interaction is needed (UI:N), the timing dependency makes success difficult and probabilistic (AC:H), the scope is unchanged (S:U), and only integrity is damaged (I:H) while confidentiality and availability are untouched. Affected builds span the Windows 10 1809/21H2/22H2 servicing branches, Windows 11 23H2/24H2/25H2/26H1/26H2, and Windows Server 2019, 2022, and 2025 including Server Core installations, as enumerated in the EUVD version ranges. Note a data-quality discrepancy worth flagging to consumers: the supplied tags label this an Information Disclosure issue, but the assessed and vendor vectors show no confidentiality impact at all and only integrity/tampering impact, so the tag should not be used for triage. No structured CPE strings were supplied in the source data, so affected versions are enumerated from the EUVD ranges rather than CPE matching.

Know when Windows gets its next vulnerability

  • Watch products and get an email when something new is published
  • Check this CVE against your own stack and servers
  • Exploit and PoC references, threat intelligence from 22 sources

No credit card · 7-day full trial

Severity by source

Vendor (microsoft) PRIMARY 4.7 MEDIUM
AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
vuln.today AI 4.7 MEDIUM

Local-only MDM access (AV:L) with an existing low-priv account (PR:L); the TOCTOU timing window forces AC:H; impact is tampering-only, so C:N/I:H/A:N.

3.1 AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
4.0 AV:L/AC:H/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (microsoft).

CVSS VectorVendor: microsoft

Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

Lifecycle Timeline

2
Patch available
Oct 13, 2026 - 20:20 EUVD
CVE Published
Oct 13, 2026 - 19:20 cve.org
MEDIUM 4.7

DescriptionCVE.org

Time-of-check time-of-use (toctou) race condition in Windows Modern Device Management (MDM) allows an authorized attacker to perform tampering locally.

Threat Intelligence Overview

EPSS Score
0.2%
Top 91% exploitable
Prevalence
Ubiquitous
Windows OS and Server across all supported versions; vast enterprise footprint
Vendor Status
Publicly Disclosed:No
Exploited:No
Latest Software Release:Exploitation Unlikely
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Defer
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

24
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +24
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0
CVE-2025-52691 CRITICAL POC
10.0 Dec 29

Unauthenticated remote code execution in SmarterTools SmarterMail lets an attacker upload arbitrary files to any locatio

CVE-2019-0803 HIGH POC
7.8 Apr 09

Windows Win32k fails to properly handle objects in memory, allowing local privilege escalation exploited in the wild in

CVE-2020-1472 MEDIUM POC
5.5 Aug 17

A privilege escalation vulnerability (CVSS 5.5). Risk factors: actively exploited (KEV-listed), EPSS 94% exploitation pr

CVE-2025-33053 HIGH POC
8.8 Jun 10

Windows Internet Shortcut Files (.url) contain an external control vulnerability (CVE-2025-33053, CVSS 8.8) that enables

CVE-2025-33073 HIGH POC
8.8 Jun 10

Windows SMB contains an improper access control vulnerability (CVE-2025-33073, CVSS 8.8) enabling authenticated attacker

CVE-2013-10047 CRITICAL POC
9.3 Aug 01

An unrestricted file upload vulnerability exists in MiniWeb HTTP Server <= Build 300 that allows unauthenticated remote

CVE-2012-10030 CRITICAL POC
9.3 Aug 05

FreeFloat FTP Server contains multiple critical design flaws that allow unauthenticated remote attackers to upload arbit

CVE-2025-34101 CRITICAL POC
9.3 Jul 10

Serviio Media Server versions 1.4 through 1.8 on Windows contain an unauthenticated command injection in the /rest/actio

CVE-2025-34095 CRITICAL POC
9.3 Jul 10

Mako Server versions 2.5 and 2.6 contain an unauthenticated OS command injection via the tutorial interface at examples/

CVE-2025-11953 CRITICAL POC
9.8 Nov 03

React Native Metro Development Server binds to external interfaces by default and contains an OS command injection endpo

CVE-2026-96951 HIGH POC
8.8 Oct 13

Command injection in the Windows Shell lets remote, unauthenticated attackers bypass a Windows security feature and then

CVE-2025-24054 MEDIUM POC
6.5 Mar 11

External control of file name or path in Windows NTLM allows an unauthorized attacker to perform spoofing over a network

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy