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Windows MDM CVE-2026-85833

| EUVDEUVD-2026-99542 HIGH
Use After Free (CWE-416)
2026-10-13 secure@microsoft.com GHSA-g53c-p2fr-76vm
7.8
CVSS 3.1 · Vendor: microsoft
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Attack ChainAIDerived

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

  1. Access
    Obtain low-privileged local foothold
  2. Delivery
    Invoke vulnerable MDM code path
  3. Exploit
    Trigger use-after-free on freed object
  4. Execution
    Reclaim memory with controlled data
  5. Impact
    Execute code as SYSTEM

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Memory lifecycle management
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires the attacker to already have local, authenticated code-execution ability as a low-privileged user on the affected Windows host (AV:L, PR:L) - this is not remotely reachable and needs no victim interaction (UI:N). The flaw lies in the Windows Modern Device Management (MDM) subsystem, so the vulnerable code path must be reachable from the attacker's session; successful exploitation also depends on winning the use-after-free race/heap-grooming to reclaim the freed object. Limiting factors that reduce real-world risk: the mandatory pre-existing local foothold (no network vector), and that all listed OS builds must be below the patched version levels given in the EUVD data (e.g., Windows 11 24H2 below 10.0.26100.9711, Server 2025 below 10.0.26100.33650).

Impact

This is a moderate-priority local privilege escalation. The CVSS 3.1 base score of 7.8 (High) is driven by high confidentiality, integrity, and availability impact (C:H/I:H/A:H), but the attack vector is strictly local (AV:L) with low attack complexity (AC:L) and requires pre-existing low-level privileges (PR:L), with no user interaction (UI:N). No EPSS probability was provided in the input, there is no CISA KEV listing, and no public proof-of-concept was identified - so by the precision rules this is 'no public exploit identified at time of analysis.' All three key exploitation signals (EPSS, KEV, POC) are therefore absent, which argues against treating this as an urgent, widely-exploited threat despite the High base score. The realistic risk is that this is a reliable second-stage privilege-escalation primitive (SYSTEM from a standard account) rather than an initial-access or remotely-triggerable flaw: an attacker must already have the ability to execute code locally as an authenticated user. Because the product is Windows (ubiquitous) and Microsoft has shipped a patch, this should be prioritized within normal Patch-Tuesday cadence for endpoint and server fleets, elevated where untrusted users can run code locally. All signals here are consistent; the only notable gap is the absence of EPSS/KEV/POC data, which lowers rather than raises urgency.

Exploit ScenarioDerived

A low-privileged authenticated user (or malware already running under a standard account) executes code that interacts with the Windows Modern Device Management (MDM) component to trigger a use-after-free condition. By grooming the freed object, the attacker reclaims the memory with attacker-controlled data and hijacks execution to run code as SYSTEM, achieving full local privilege escalation. No public exploit code has been identified at time of analysis, and no user interaction is required.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 13, 2026

Local privilege escalation in the Windows Modern Device Management (MDM) component allows an authenticated low-privileged user who already has code execution on a Windows host to gain SYSTEM-level privileges by triggering a use-after-free in the MDM code path. The flaw is rated CVSS 7.8 (AV:L/AC:L/PR:L/UI:N), meaning it is not remotely reachable, requires no victim interaction, and depends on the attacker already holding a local foothold; successful exploitation also requires winning the heap-reuse race to reclaim the freed object. Consistent with our independent assessment this is a moderate-priority local escalation issue, and no public exploit identified at time of analysis; Microsoft has released patches through its update guide.

RemediationAI

Patch available per vendor advisory: apply the current Microsoft security update for each affected build through the MSRC update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85833, which is the authoritative source for the exact KB numbers. As orientation, the EUVD build thresholds indicate the fixed levels to reach or exceed - 10.0.14393.9612 for Windows 10 1607 / Server 2016, 10.0.17763.9376 for Windows 10 1809 / Server 2019, 10.0.19044.7807 for Windows 10 21H2 and 22H2, 10.0.20348.5761 for Server 2022, 6.3.9600.23470 for Server 2012 R2, 10.0.22631.7652 for Windows 11 23H2, 10.0.26100.9711 for Windows 11 24H2 and 10.0.26100.33650 for Server 2025, 10.0.26200.9711 for Windows 11 25H2, 10.0.26300.9711 for Windows 11 26H2, and 10.0.28000.3231 for Windows 11 26H1 - but verify the mapping against the advisory rather than treating these as substitute KB guidance. Because exploitation requires a pre-existing local authenticated foothold (AV:L/PR:L), the highest-value compensating controls are reducing the local attack surface: enforce least privilege and remove unnecessary local administrator and interactive logon rights (trade-off: operational friction for helpdesk and admin workflows), apply WDAC or AppLocker in enforced mode to block execution of untrusted binaries and scripts from user-writable paths such as %TEMP%, Downloads, and user profiles (trade-off: requires an allow-list maintenance process and can break line-of-business apps), and enable Windows Defender Exploit Protection mitigations - particularly heap integrity, force-randomized images, and Control Flow Guard enforcement - for MDM-related host processes (trade-off: occasional application incompatibility and modest performance overhead). Where MDM is not actually used in the environment, disabling or restricting the MDM enrollment/policy channel to managed administrators only reduces reachable code paths, though it can interfere with existing Intune or third-party enrollment and should be tested first; monitor endpoint telemetry for unusual MDM worker process crashes, repeated low-privileged processes spawning high-integrity children, and SYSTEM-level token anomalies as indicators of exploitation attempts.

Affected VersionsENISA

Windows Server 2012 R2 (Server Core installation) 6.3.9600.0 <6.3.9600.23470
Windows Server 2022 10.0.20348.0 <10.0.20348.5761
Windows Server 2016 10.0.14393.0 <10.0.14393.9612
Windows 10 Version 1607 10.0.14393.0 <10.0.14393.9612
Windows 10 Version 22H2 10.0.19045.0 <10.0.19044.7807
Windows Server 2025 10.0.26100.0 <10.0.26100.33650
Windows 11 Version 24H2 10.0.26100.0 <10.0.26100.9711
Windows Server 2019 10.0.17763.0 <10.0.17763.9376
Windows Server 2016 (Server Core installation) 10.0.14393.0 <10.0.14393.9612
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 21H2 10.0.19044.0 <10.0.19044.7807
Windows Server 2025 (Server Core installation) 10.0.26100.0 <10.0.26100.33650
Windows 11 Version 23H2 10.0.22631.0 <10.0.22631.7652
Windows Server 2019 (Server Core installation) 10.0.17763.0 <10.0.17763.9376
Windows 10 Version 1809 10.0.17763.0 <10.0.17763.9376
Windows 11 version 26H1 10.0.28000.0 <10.0.28000.3231
Windows Server 2012 R2 6.3.9600.0 <6.3.9600.23470

Affected Packages

euvd windows_10_version_1607 fix: 10.0.14393.9612
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_2012_r2 fix: 6.3.9600.23470
euvd windows_server_2012_r2_server_core_installation fix: 6.3.9600.23470
euvd windows_server_2016 fix: 10.0.14393.9612
euvd windows_server_2016_server_core_installation fix: 10.0.14393.9612
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 18 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 is CWE-416, use after free, in the Windows Modern Device Management (MDM) subsystem - the stack that processes MDM configuration/CSP policy on managed Windows clients and servers. In a use-after-free, the vulnerable code frees a heap object (typically MDM-related configuration or session state) but continues to reference the dangling pointer; an attacker who can influence the object's lifetime can perform heap grooming so that the freed memory is reallocated with attacker-controlled contents, resulting in memory corruption that is redirected into privilege escalation. Intelligence tags for this CVE include memory corruption and denial of service, which is consistent with a UAF primitive that can crash or corrupt the process before it is shaped into a reliable escalation. The CVSS vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H confirms the attacker must already be operating locally as a low-privileged, authenticated user (PR:L), with no user interaction needed (UI:N), and that a successful exploit yields high confidentiality, integrity, and availability impact within the same security scope. The affected surface spans the entire modern Windows client and server line, with EUVD-supplied CPE-style build ranges covering Windows 10, Windows 11, and Windows Server 2012 R2 through 2025, including Server Core installations.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (microsoft) PRIMARY 7.8 HIGH
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vuln.today AI 7.8 HIGH

Local use-after-free EoP requiring an existing low-privileged account (AV:L, PR:L), no interaction, yielding SYSTEM-level control over confidentiality, integrity and availability (C/I/A:H).

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

Primary rating from Vendor (microsoft).

CVSS VectorVendor: microsoft

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

Lifecycle Timeline

2
Patch available
Oct 13, 2026 - 20:20 EUVD
CVE Published
Oct 13, 2026 - 19:21 cve.org
HIGH 7.8

DescriptionCVE.org

Use after free in Windows Modern Device Management (MDM) allows an authorized attacker to elevate privileges locally.

Executive ViewAI

Why It Matters

A high-severity local privilege escalation vulnerability in the Windows Modern Device Management (MDM) component could allow an authenticated attacker with an existing low-privileged foothold on a Windows host to gain SYSTEM-level privileges. This matters to leadership because a successful exploit turns a limited breach into full control of the endpoint, enabling broader credential theft, lateral movement, and data access across managed Windows devices. No public exploit has been identified at time of analysis, and Microsoft has released patches via its update guide.

Business Impact: Medium
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.3%
Top 77% exploitable
Prevalence
Ubiquitous
Windows OS present in a huge fraction of enterprise and consumer environments
Vendor Status
Publicly Disclosed:No
Exploited:No
Latest Software Release:Exploitation Less Likely
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 HIGH
CISA KEV No
Public POC No
EPSS 0.3%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
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
Defer
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact
Medium
Technical Impact
Total

Priority Score

39
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +39
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Use-after-free vulnerabilities occur when a program continues to access memory through a pointer after that memory has been deallocated.

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

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