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Attack ChainAIDerived

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

  1. Access
    Obtain low-privileged local access
  2. Delivery
    Interact with Windows Work Folders component
  3. Exploit
    Trigger use-after-free via timing/heap reuse
  4. Execution
    Corrupt freed object to hijack control
  5. Impact
    Elevate to higher privilege locally

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 authenticated, low-privileged local access (PR:L, AV:L) to a Windows system where the Work Folders feature/component is present and in use, and to reliably win the use-after-free race/timing window (AC:H). Limiting factors that reduce realistic risk: no remote vector (must have a local foothold first), existing authentication required, and high attack complexity meaning exploitation is not trivially reliable. No user interaction is needed (UI:N). The flaw does not provide initial access - it is a post-compromise privilege-escalation step against hosts running the affected Work Folders code paths.

Impact

This is a genuine but not top-tier priority. The CVSS 3.1 vector (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H, base 7.0 HIGH) describes a local privilege-escalation requiring an attacker to already hold low-level privileges (PR:L) on the host and to win a difficult-to-engineer race/memory-corruption condition (AC:H), yielding total compromise of confidentiality, integrity and availability. The CISA SSVC framework corroborates a lower operational urgency: Exploitation status is 'none' (no observed exploitation), Automatable is 'no' (consistent with AC:H and the need for prior local access), though Technical Impact is 'total' (consistent with C:H/I:H/A:H). There is no CISA KEV listing and no POC referenced in the input, so exploitation status is 'no public exploit identified at time of analysis'. No EPSS score was provided, so probabilistic exploitation likelihood cannot be factored in - STATE EXPLICITLY: EPSS data is MISSING. The signals are internally consistent rather than conflicting: a local, high-complexity, authenticated UAF with no evidence of exploitation. The realistic verdict is a reliable second-stage escalation primitive for an attacker who already has a foothold, not a wormable or remotely-reachable emergency. Given the ubiquity of Windows, patch prioritization is still warranted, but it sits below any network-reachable or actively-exploited flaw.

Exploit ScenarioDerived

An attacker who has already gained low-privileged code execution on a Windows host (e.g., via phishing or a prior foothold) triggers a use-after-free in the Work Folders component by carefully timing operations to reuse freed memory. By grooming the heap and winning the race condition (high complexity), they corrupt kernel/service state to execute code at elevated privilege. No public exploit code is identified at time of analysis, and the high attack complexity makes reliable weaponization non-trivial.

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 14, 2026

Local privilege escalation in Windows Work Folders allows an attacker who already holds authenticated, low-privileged access on an affected Windows 10, Windows 11, or Windows Server host to trigger a use-after-free in the Work Folders code path, corrupting memory and potentially executing code with elevated privileges. The independently assessed vector (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H, base 7.0) confirms this is a post-compromise escalation step that requires an existing local foothold and a reliably won race/timing window, with no user interaction; there is no public exploit identified at time of analysis and CISA's SSVC assessment records exploitation as none and automatable as no. Microsoft has released fixed builds through the MSRC update guide, so the primary risk is to unpatched hosts where the Work Folders feature is present and in use.

RemediationAI

Apply the vendor patch: Microsoft lists an update for CVE-2026-70045 in the MSRC Security Update Guide (https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-70045), and installing the current cumulative security update for each affected build delivers the fix at or above the EUVD fix boundaries - 10.0.17763.9376 for Windows 10 1809 / Server 2019, 10.0.19044.7807 for Windows 10 21H2/22H2, 10.0.22631.7652 for Windows 11 23H2, 10.0.26100.9711 for Windows 11 24H2, 10.0.26200.9711 for Windows 11 25H2, 10.0.26300.9711 for Windows 11 26H2, 10.0.28000.3231 for Windows 11 26H1, and 10.0.26100.33650 for Windows Server 2025 (including Server Core); patch status is 'Patch available per vendor advisory', and no exact fix package/version numbers beyond these build levels are provided in the source data. Because the flaw is a local, authenticated, post-compromise privilege escalation (AV:L/PR:L, AC:H) and not remotely reachable, the highest-value compensating controls are to remove the attack surface where possible and tighten local privilege boundaries: if Work Folders is not in use, uninstall or disable the feature (client via 'Turn Windows features on or off' or the Work Folders control panel, server via Remove-WindowsFeature WorkFolders-Server), accepting the trade-off that synchronization and any configured sync shares stop functioning; note that this is only effective where the feature is genuinely not needed, since the underlying code may be serviced by other components. Additionally, restrict interactive and remote interactive logon to trusted administrative accounts and enforce least privilege so that unprivileged local users cannot be positioned to trigger the use-after-free, and monitor for unusual Work Folders sync process crashes or anomalous child processes as indicators of attempted exploitation. Adding a rebase/restart step after patching ensures the vulnerable sync process is replaced, and there is no indication of active exploitation (SSVC exploitation: none), so remediation can follow normal patch-cycle prioritization rather than emergency response.

Affected VersionsENISA

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

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_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 12 packages in euvd

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

Technical ContextAI · show details

Windows Work Folders is a Microsoft sync feature (client sync engine plus server-side sync share/sync service components, available since Windows 8.1/Server 2012 R2) that keeps user data synchronized between endpoints and a file server hosting a sync share; it exposes both a client-side sync process and server-side sync service code paths that run with elevated privileges. The root cause class is CWE-416 (use after free): a heap object is released while a dangling reference is still dereferenced, which under the right heap grooming conditions produces memory corruption (the input tags also classify this as memory corruption and a denial-of-service risk), and can be leveraged for arbitrary code execution in the security context of the vulnerable component. The assessed vector AV:L/PR:L places the attacker on the local machine with only low privileges and requires authentication, while AC:H reflects the need to reliably win the use-after-free race/timing window; UI:N means no victim interaction is needed, and S:U indicates privilege gain stays within the same security authority. Affected binaries span the client and server editions enumerated in the EUVD version ranges, including Windows 10 (1809, 21H2, 22H2), Windows 11 (23H2, 24H2, 25H2, 26H1, 26H2), Windows Server 2019, and Windows Server 2025 (including Server Core installations), so the flaw is present wherever the Work Folders feature and its sync-related code paths are installed.

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  • Exploit and PoC references, threat intelligence from 22 sources

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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
vuln.today AI 7.0 HIGH

Local privilege escalation requiring a prior authenticated foothold (PR:L) and winning a UAF race (AC:H); no user interaction, with total CIA impact on the host.

3.1 AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
4.0 AV:L/AC:H/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
High
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 - 19:19 cve.org
HIGH 7.0

DescriptionCVE.org

Use after free in Windows Work Folders allows an authorized attacker to elevate privileges locally.

Executive ViewAI

Why It Matters

A high-severity local privilege escalation flaw in the Windows Work Folders feature affects Windows 10, Windows 11, and Windows Server hosts where that feature is enabled, allowing an attacker who already has a low-privileged foothold on a machine to escalate to elevated system rights. Because the flaw is local and requires an existing compromise, the direct exposure to outside attackers is limited, but any host already touched by malware, a malicious insider, or an unsecured service account can use it to convert limited access into full control of that system. Leadership should care because unpatched, Work Folders-enabled endpoints and servers represent a leverage point that can turn a contained incident into a domain-wide one, and patching is straightforward and already available.

Business Impact: High
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.3%
Top 82% exploitable
Prevalence
Ubiquitous
Windows is deployed across 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
High
Technical Impact
Total

Priority Score

35
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +35
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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