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Attack ChainAIDerived

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

  1. Access
    Gain local low-privileged user session
  2. Delivery
    Locate and interact with File History Service process
  3. Exploit
    Perform heap-grooming to achieve required memory layout
  4. Execution
    Trigger use-after-free dereference
  5. Persist
    Corrupt service execution flow
  6. Impact
    Obtain SYSTEM-level privilege escalation

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 a locally authenticated account with standard (low-privileged) user rights and interactive logon access to the target system - remote exploitation is not possible per the AV:L CVSS metric. The Windows File History Service must be present and active; it is enabled by default on Windows 10 and Windows 11 workstation editions but may be absent or stopped on Server installations where File History is not configured. The AC:H metric indicates that successful exploitation additionally requires achieving a specific heap memory state, likely through precise allocation sequencing or race-condition timing - this is a concrete technical barrier that distinguishes this from trivially automatable EoP bugs. No special application configuration or non-default feature beyond local user access and the File History Service being active is required. Exploitation is limited to physical or remote-desktop sessions - purely remote network-based exploitation is not applicable.

Impact

The CVSS 7.0 score with AV:L/AC:H/PR:L correctly positions this as a meaningful but not trivially exploitable local privilege escalation. The local-only attack vector significantly limits exposure compared to network-reachable vulnerabilities - an attacker must already have interactive access to the target system. The high complexity metric reflects genuine exploit development difficulty: UAF exploitation requires careful heap grooming and is not reliably achievable without dedicated effort and target-specific knowledge. EPSS data is absent from the input, making probabilistic exploitation forecasting unavailable; however, UAF techniques are well-documented in public exploit literature and skilled threat actors regularly achieve reliable UAF exploitation given sufficient analysis time. No CISA KEV listing and no public exploit code exist at time of analysis. Even a mid-sized municipal IT team in boleslawiec maintaining a mixed Windows 10/11 fleet should treat this as a routine patch-cycle priority rather than an emergency - the AC:H bar moderates urgency relative to AC:L privilege escalation bugs, but the full C:H/I:H/A:H impact upon success and the ubiquitous Windows footprint sustain meaningful residual risk for any delayed patching.

Exploit ScenarioDerived

A low-privileged user with interactive logon access to an unpatched Windows 10 or Windows 11 workstation identifies the File History Service process and crafts a sequence of memory allocation and deallocation operations designed to achieve a specific heap layout. After triggering the use-after-free condition - likely requiring multiple attempts to achieve reliable timing - the attacker redirects execution to controlled memory and gains SYSTEM-level privileges, then installs a persistent backdoor or dumps LSASS credentials for lateral movement. No public exploit code has been identified, meaning this scenario currently demands significant exploit-development expertise.

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 – Sep 09, 2026

Privilege escalation in Windows File History Service across Windows 10, Windows 11, and Windows Server 2016/2019 allows a locally authenticated low-privileged attacker to gain SYSTEM-level access by exploiting a use-after-free memory corruption flaw (CWE-416) in the service process. The CVSS 7.0 score reflects real exploitation difficulty - attack complexity is high, indicating dependence on heap layout conditions or race-condition timing typical of UAF bugs. No public exploit code or active exploitation has been identified at time of analysis, and a vendor-released patch is available from Microsoft.

RemediationAI

Apply the Microsoft security update for the relevant Windows release via Windows Update, WSUS, or Microsoft Update Catalog. Fixed build versions confirmed by EUVD data are: 10.0.14393.9512 for Windows 10 1607 and Windows Server 2016 (including Server Core); 10.0.17763.9245 for Windows 10 1809 and Windows Server 2019 (including Server Core); 10.0.19044.7725 for Windows 10 21H2; 10.0.19045.7725 for Windows 10 22H2; 10.0.22631.7582 for Windows 11 23H2; 10.0.26100.9445 for Windows 11 24H2; 10.0.26200.9445 for Windows 11 25H2; and 10.0.28000.2954 for Windows 11 26H1. The full update guide is at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-71340. Where immediate patching is not feasible, restricting interactive logon rights (via Group Policy or local security policy) to only trusted users shrinks the exploitable population, since exploitation requires an active local session. Disabling the File History feature via Group Policy (Computer Configuration > Administrative Templates > Windows Components > File History > Turn off File History) may reduce service-level attack surface but eliminates backup functionality - assess the operational trade-off before applying.

Affected VersionsENISA

Windows Server 2016 10.0.14393.0 <10.0.14393.9512
Windows Server 2019 (Server Core installation) 10.0.17763.0 <10.0.17763.9245
Windows Server 2016 (Server Core installation) 10.0.14393.0 <10.0.14393.9512
Windows 11 version 26H1 10.0.28000.0 <10.0.28000.2954
Windows 11 Version 25H2 10.0.26200.0 <10.0.26200.9445
Windows 11 Version 24H2 10.0.26100.0 <10.0.26100.9445
Windows 10 Version 1809 10.0.17763.0 <10.0.17763.9245
Windows Server 2019 10.0.17763.0 <10.0.17763.9245
Windows 10 Version 21H2 10.0.19044.0 <10.0.19044.7725
Windows 11 Version 23H2 10.0.22631.0 <10.0.22631.7582
Windows 10 Version 1607 10.0.14393.0 <10.0.14393.9512
Windows 10 Version 22H2 10.0.19045.0 <10.0.19045.7725

Affected Packages

euvd windows_10_version_1607 fix: 10.0.14393.9512
euvd windows_10_version_1809 fix: 10.0.17763.9245
euvd windows_10_version_21h2 fix: 10.0.19044.7725
euvd windows_10_version_22h2 fix: 10.0.19045.7725
euvd windows_11_version_23h2 fix: 10.0.22631.7582
euvd windows_11_version_24h2 fix: 10.0.26100.9445
euvd windows_11_version_25h2 fix: 10.0.26200.9445
euvd windows_11_version_26h1 fix: 10.0.28000.2954
euvd windows_server_2016 fix: 10.0.14393.9512
euvd windows_server_2016_server_core_installation fix: 10.0.14393.9512
euvd windows_server_2019 fix: 10.0.17763.9245
euvd windows_server_2019_server_core_installation fix: 10.0.17763.9245

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

The Windows File History Service is a built-in Windows component responsible for automated file versioning and backup. CWE-416 (Use After Free) arises when a program dereferences a pointer after the underlying memory has been freed, enabling an attacker with precise heap-grooming capabilities to redirect execution or corrupt kernel/service data structures. Because the File History Service process executes with elevated permissions relative to a standard user, a successful UAF exploit in this service permits privilege escalation to SYSTEM. The AC:H CVSS metric indicates that achieving reliable exploitation requires specific memory conditions - heap-spray techniques, timing manipulation, or specific allocation/deallocation sequencing are likely prerequisites. Affected products span a wide Windows build range: Windows 10 versions 1607 through 22H2, Windows 11 versions 23H2 through 26H1, and Windows Server 2016/2019, as confirmed by EUVD-2026-73096 with explicit build-number boundaries.

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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-only UAF requiring low-privileged access and high-complexity heap manipulation; full C/I/A impact reflects SYSTEM-level privilege gain post-exploitation.

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:P/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
Sep 08, 2026 - 18:35 EUVD
CVE Published
Sep 08, 2026 - 18:20 nvd
HIGH 7.0

DescriptionCVE.org

Use after free in Windows File History Service allows an authorized attacker to elevate privileges locally.

Executive ViewAI

Why It Matters

The Windows File History Service on Windows 10, Windows 11, and Windows Server 2016/2019 is vulnerable to local privilege escalation allowing authenticated standard users to gain SYSTEM-level control. This vulnerability enables lateral movement, data exfiltration, and malware installation by any user with local access, affecting all organizations deploying these Windows versions. Immediate patching is critical to prevent both insider threats and post-compromise lateral movement.

Business Impact: High
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.3%
Top 81% exploitable
Prevalence
Ubiquitous
Windows OS present across virtually all enterprise and consumer environments
Vendor Status
Publicly Disclosed:No
Exploited:No
Latest Software Release:Exploitation More 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

Privilege escalation occurs when an attacker leverages flaws in access control mechanisms to gain permissions beyond what they were originally granted.

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.

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