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Windows Storage CVE-2026-96944

| EUVDEUVD-2026-100267 MEDIUM
Insertion of Sensitive Information into Externally-Accessible File (CWE-538)
2026-10-13 secure@microsoft.com GHSA-c6mc-4444-xhwp
5.5
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 authenticated local session
  2. Exploit
    Access externally-readable Windows Storage file
  3. Execution
    Read improperly stored sensitive data
  4. Impact
    Disclose information to attacker

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V14 - Data Protection Sensitive file access control
Exploitation Conditions

Exploitation requires the attacker to already have an authenticated, interactive local session on the affected Windows host (AV:L, PR:L = valid low-privileged credentials), with no user interaction needed (UI:N). The flaw is the Windows Storage component placing sensitive information into a file or directory that is accessible to lower-privileged users than intended (CWE-538); the attacker simply reads that externally-accessible location. LIMITING FACTORS: it cannot be exploited remotely or by an unauthenticated user, impact is confidentiality-only (no integrity or availability loss, S:U so no privilege/scope escalation), and affected systems must be unpatched Windows 11 (builds below 24H2 10.0.26100.9711 / 25H2 10.0.26200.9711 / 26H1 10.0.28000.3231 / 26H2 10.0.26300.9711) or Windows Server 2022 (<10.0.20348.5761) / 2025 (<10.0.26100.33650).

Impact

This is a moderate-severity information disclosure flaw (CVSS 5.5) with multiple signals pointing to LOW real-world urgency. The CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N) requires LOCAL access and LOW privileges (PR:L = an authenticated, logged-on user), limiting it to attackers who already have a foothold on the host - it is not remotely exploitable. CISA's SSVC decision framework reinforces this: Exploitation=none (no observed or public exploitation), Automatable=no (cannot be mass-scaled), Technical Impact=partial. No EPSS score was provided in the input, and the CVE is NOT on the CISA KEV list, so there is no evidence of active exploitation. No POC/exploit code is referenced. The signals are consistent rather than conflicting: a confidentiality-only (C:H/I:N/A:N) local disclosure bug that Microsoft self-reported and has already patched. Verdict: a legitimate patch-in-normal-cycle issue, NOT an emergency - the high confidentiality impact is tempered by the local attack vector and required authentication, making widespread or automated exploitation unlikely.

Exploit ScenarioDerived

An attacker who has already gained an authenticated local session on a Windows host (e.g., a standard low-privileged user or via prior compromise) abuses the Windows Storage component to read sensitive information that was improperly written into an externally-accessible file or directory (CWE-538). Because the CVSS vector is AV:L/PR:L, this requires existing local access and low-level privileges - it cannot be triggered remotely or by an anonymous user. No public exploit identified at time of analysis.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.5% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 13, 2026

Information disclosure in the Microsoft Windows Storage component lets an authenticated local attacker read sensitive data that the service places in a file or directory reachable by lower-privileged users (CWE-538). Exploitation requires a valid low-privileged interactive session on an unpatched host (CVSS:3.1/AV:L/AC:L/PR:L/UI:N), so it cannot be triggered remotely or by an unauthenticated user, and the impact is confidentiality-only (C:H, I:N, A:N) with a base score of 5.5. Microsoft has released fixes, CISA's SSVC assessment rates exploitation as 'none' with automatable 'no', and no public exploit code has been identified at time of analysis, making this a moderate-severity hardening item rather than an urgent remote threat.

RemediationAI

Apply the Microsoft security update corresponding to your build: Windows 11 24H2 to 10.0.26100.9711 or later, Windows 11 25H2 to 10.0.26200.9711 or later, Windows 11 26H1 to 10.0.28000.3231 or later, Windows 11 26H2 to 10.0.26300.9711 or later, Windows Server 2022 to 10.0.20348.5761 or later, and Windows Server 2025 (including Server Core) to 10.0.26100.33650 or later, per the MSRC update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-96944. Vendor-released patch: available per the MSRC advisory, so prioritization is routine patch-cycle rather than emergency; the fixed builds above are the exact versions to verify. Where immediate patching is not possible, compensating controls are limited and have trade-offs: audit and tighten ACLs on storage-related data directories and any service-created log or cache paths so that only Administrators and SYSTEM can read them - this can break backup, monitoring, or third-party storage agents that rely on those paths and must be validated first; reduce the number of local interactive accounts on servers and workstations and remove unnecessary local logon rights, which shrinks the PR:L attack surface but may disrupt legitimate operator workflows; and detect post-patch regression by monitoring for low-privileged processes reading storage service directories. Because the flaw is local and requires existing credentials, network segmentation, remote-access hardening, and egress filtering provide no meaningful protection against this specific issue, and no public exploit code or in-the-wild activity has been identified, so effort is best spent on inventorying unpatched builds and scheduling the update.

Affected VersionsENISA

Windows 11 version 26H1 10.0.28000.0 <10.0.28000.3231
Windows 11 Version 26H2 10.0.26300.0 <10.0.26300.9711
Windows 11 Version 24H2 10.0.26100.0 <10.0.26100.9711
Windows 11 Version 25H2 10.0.26200.0 <10.0.26200.9711
Windows Server 2022 10.0.20348.0 <10.0.20348.5761
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

Affected Packages

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_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 7 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-538, 'Insertion of Sensitive Information into Externally-Accessible File or Directory.' Windows Storage - the user-mode services and drivers that manage storage spaces, disks, volumes, and storage-related metadata - writes data to a location whose permissions or visibility are broader than the sensitivity of the content warrants. Rather than a memory-safety bug, this is a design/permission defect: information that should be confined to privileged contexts ends up in a path that a non-administrative local user can enumerate and read. The CVSS vector (AV:L, PR:L, UI:N, S:U) confirms the attacker must already hold valid low-privileged credentials on the machine and needs no further user interaction or privilege change; the only security property lost is confidentiality, but the information leaked is rated High because it may include secrets useful for lateral movement or further escalation. It is neither remote nor network-automatable, consistent with the SSVC 'Automatable: no' and 'Exploitation: none' ratings.

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Severity by source

Vendor (microsoft) PRIMARY 5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
vuln.today AI 5.5 MEDIUM

Local access and valid low-privilege credentials are required (AV:L, PR:L), no interaction needed; impact is confidentiality-only disclosure (C:H, I:N, A:N) with no scope change.

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
4.0 AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/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
None
Availability
None

Lifecycle Timeline

2
Patch available
Oct 13, 2026 - 20:20 EUVD
CVE Published
Oct 13, 2026 - 19:22 cve.org
MEDIUM 5.5

DescriptionCVE.org

Insertion of sensitive information into externally-accessible file or directory in Windows Storage allows an authorized attacker to disclose information locally.

Threat Intelligence Overview

EPSS Score
0.5%
Top 61% exploitable
Prevalence
Ubiquitous
Core Windows 11 and Windows Server component in most enterprise 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 MEDIUM
CISA KEV No
Public POC No
EPSS 0.5%
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

28
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +28
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

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