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Vulnerability Assessment

Weakness
CWE
CWE-416
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.

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This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Jul 23, 2026

Local privilege escalation in the Windows Projected File System (ProjFS) affects the full supported Windows line — Windows 10 (1809/21H2/22H2), Windows 11 (22H3 through 26H1), and Windows Server 2019/2022/2025 — where a use-after-free (CWE-416) lets an authenticated local user corrupt kernel/service memory and elevate to higher privileges. Microsoft-reported and patched, the flaw carries total technical impact per CISA SSVC but has no public exploit identified at time of analysis and a very low EPSS (0.04%). The high attack complexity (AV:L/AC:H) reflects a race-condition-style UAF that is non-trivial to win reliably.

Affected VersionsENISA

Windows 11 version 26H1 10.0.28000.0 <10.0.28000.2113
Windows Server 2022 10.0.20348.0 <10.0.20348.5139
Windows Server 2019 (Server Core installation) 10.0.17763.0 <10.0.17763.8755
Windows 11 Version 24H2 10.0.26100.0 <10.0.26100.8457
Windows Server 2025 (Server Core installation) 10.0.26100.0 <10.0.26100.32860
Windows Server 2025 10.0.26100.0 <10.0.26100.32860
Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.0 <10.0.25398.2330
Windows 11 version 22H3 10.0.22631.0 <10.0.22631.7079
Windows 11 Version 23H2 10.0.22631.0 <10.0.22631.7079
Windows 10 Version 1809 10.0.17763.0 <10.0.17763.8755
Windows 10 Version 22H2 10.0.19045.0 <10.0.19045.7291
Windows Server 2019 10.0.17763.0 <10.0.17763.8755
Windows 11 Version 25H2 10.0.26200.0 <10.0.26200.8457
Windows 10 Version 21H2 10.0.19044.0 <10.0.19044.7291

Affected Packages

euvd windows_10_version_1809 fix: 10.0.17763.8755
euvd windows_10_version_21h2 fix: 10.0.19044.7291
euvd windows_10_version_22h2 fix: 10.0.19045.7291
euvd windows_11_version_22h3 fix: 10.0.22631.7079
euvd windows_11_version_23h2 fix: 10.0.22631.7079
euvd windows_11_version_24h2 fix: 10.0.26100.8457
euvd windows_11_version_25h2 fix: 10.0.26200.8457
euvd windows_11_version_26h1 fix: 10.0.28000.2113
euvd windows_server_2019 fix: 10.0.17763.8755
euvd windows_server_2019_server_core_installation fix: 10.0.17763.8755
euvd windows_server_2022 fix: 10.0.20348.5139
euvd windows_server_2022_23h2_edition_server_core_installation fix: 10.0.25398.2330
euvd windows_server_2025 fix: 10.0.26100.32860
euvd windows_server_2025_server_core_installation fix: 10.0.26100.32860

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 14 packages in euvd

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  • Exploit and PoC references, threat intelligence from 22 sources
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Severity by source

NVD PRIMARY 7.0 HIGH
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
ENISA EUVD HIGH
CIRCL (temporal) 6.1 MEDIUM

Primary rating from NVD.

CVSS VectorNVD

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

DescriptionCVE.org

Use after free in Windows Projected File System allows an authorized attacker to elevate privileges locally.

Executive ViewAI

Why It Matters

Windows Projected File System (ProjFS) contains a privilege escalation vulnerability (CVE-2026-34340, CVSS 7.0) affecting all supported versions of Windows 10, 11, and Windows Server 2019/2022/2025-a vulnerability impacting every Windows system across the organization's infrastructure. An authenticated local user can exploit this use-after-free flaw to gain system-level privileges; however, no public exploit identified at time of analysis reduces immediate exploitation risk. Microsoft has released a patch, making this a manageable issue requiring coordinated deployment across enterprise infrastructure.

Recommended Action

Within 24 hours: immediately inventory all Windows systems running affected versions (Windows 10 versions 1809/21H2/22H2, Windows 11 versions 22H3 through 26H1, and Windows Server 2019/2022/2025), and prioritize those with high user density or sensitive functions. Within 7 days: validate Microsoft's vendor patch in test environments, confirm stability on representative production-like systems, and begin staged deployment starting with server infrastructure and critical systems. Within 30 days: complete patch deployment organization-wide using Windows Update, WSUS, or endpoint management tools; verify patching compliance through automated reporting and close the vulnerability across all affected systems.

Business Impact: High
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.0%
Top 88% exploitable
Threat Intel
1
1 sources
Vendor Action
See Below
Required. The vulnerability documented by this CVE requires customer action to resolve.
Vendor Status
Publicly Disclosed:No
Exploited:No
Latest Software Release:Exploitation Less Likely
Data Quality
7 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment NCSC-NL MSRC VulDB

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 0.0%
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
Scheduled
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

40
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +35
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: +5

Attack Technique

Use After Free HIGH

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

Memory Corruption HIGH

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 MEDIUM

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

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Same weakness CWE-416 – Use After Free

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References

Advisories & patches
PATCH https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-34340 ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-34340 ADVISORY https://vuldb.com/vuln/363147

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