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Windows 11 CVE-2026-85916

| EUVDEUVD-2026-99625 MEDIUM
Exposure of Private Personal Information to an Unauthorized Actor (CWE-359)
2026-10-13 secure@microsoft.com GHSA-v6w9-7gr4-9fr3
5.5
CVSS 3.1 · NVD
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Attack ChainAIDerived

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

  1. Access
    Obtain local foothold on Windows host
  2. Exploit
    Access exposed AAD identity component
  3. Execution
    Read private personal information
  4. Impact
    Exfiltrate disclosed data

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V14 - Data Protection PII protection
Exploitation Conditions

Requires pre-existing local access to an affected Windows 11 (23H2 through 26H2) or Windows Server 2025 host running a vulnerable build below the patched versions (e.g. 24H2 below 10.0.26100.9711, Server 2025 below 10.0.26100.33650). The AV:L vector means the vulnerability cannot be reached over a network - the attacker must already be able to execute in a local user context. No authentication beyond that local session and no user interaction are required (PR:N/UI:N). The limiting factors are therefore the need for a local foothold and a vulnerable, unpatched OS build; patched builds and hosts without attacker-controlled local access are not exploitable.

Impact

This is a moderate-severity local information disclosure (CVSS 6.2, CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N) with multiple signals pointing to LOW real-world urgency despite the HIGH confidentiality impact. The CVSS vector is self-consistent: local attack vector (AV:L) with low complexity and no privileges (PR:N) means a user with local access, but no network reachability - which is why the base score stays at 6.2 rather than critical. CISA SSVC reinforces low priority: Exploitation=none (no observed or public exploitation), Automatable=no, and Technical Impact=partial. No EPSS score was provided, there is no CISA KEV listing, and no POC is referenced, so no public exploit identified at time of analysis. A notable data conflict exists: the description attributes the flaw to 'Azure Active Directory' (a cloud identity service), yet every affected build in the EUVD data is a local Windows 11 / Windows Server 2025 OS version - this strongly suggests the flaw is in an on-host Entra ID / AAD client component or cached credential/identity data on Windows, not in the cloud service itself; verify scope with the Microsoft MSRC advisory. Overall this is a genuine but lower-priority patch-in-normal-cycle issue, not an emergency: high data-sensitivity impact but gated behind local access and no evidence of exploitation.

Exploit ScenarioDerived

An attacker who already has local, low-privileged access to a Windows 11 or Windows Server 2025 host (for example a standard logged-in user, or malware running in a non-admin context) reads private personal information belonging to another user or identity that is improperly exposed by the Azure Active Directory / Entra client component. No authentication step or user interaction is required beyond the local foothold, but remote-only attackers cannot reach the flaw. No public exploit code is known at the 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 14, 2026

Local information disclosure in Windows 11 (23H2, 24H2, 25H2, 26H1, 26H2) and Windows Server 2025 lets anyone who already holds a local user session read private personal information they should not be able to access, yielding a HIGH confidentiality impact (CVSS 6.2, CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N) with no integrity or availability effect. The flaw is not remotely reachable and requires no authentication or user interaction beyond the local foothold, so the practical exposure is limited to hosts where an attacker has already gained local code execution on an unpatched build. No public exploit code or active exploitation has been identified at time of analysis (CISA SSVC reports Exploitation: none, Automatable: no), and the moderate score plus the local-only vector point to LOW real-world urgency even though the data disclosed is sensitive.

RemediationAI

Vendor-released patch: apply the Microsoft cumulative update that moves each affected build to its fixed revision - 10.0.22631.7652 for Windows 11 23H2, 10.0.26100.9711 for Windows 11 24H2, 10.0.26200.9711 for Windows 11 25H2, 10.0.28000.3231 for Windows 11 26H1, 10.0.26300.9711 for Windows 11 26H2, and 10.0.26100.33650 for Windows Server 2025 (including Server Core). Follow the MSRC update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85916 for the exact KB mapping, supersedence, and prerequisite servicing-stack updates, and verify post-update build numbers with winver or Get-ComputerInfo rather than relying on patch-scanning alone. Because the vector is AV:L/PR:N/UI:N, there is no network-facing service to disable or port to block; the meaningful compensating controls are to reduce the local attacker surface until patching completes - enforce least privilege so non-administrative users cannot run untrusted code on these hosts, restrict interactive logon and RDP access to trusted accounts, and tighten application allowlisting (WDAC or AppLocker) so a low-privileged foothold cannot be used to query the exposed data. The trade-off is operational friction: stricter logon restrictions and allowlisting can block legitimate line-of-business tooling and remote support workflows, and they reduce but do not eliminate exposure, since the disclosure only requires a local user context, not administrator rights. Prioritize the Server 2025 and Windows 11 24H2/25H2 fleets with the largest multi-user or shared-session exposure, and note that no vendor workaround short of patching fully closes the issue.

Affected VersionsENISA

Windows 11 Version 26H2 10.0.26300.0 <10.0.26300.9711
Windows 11 Version 23H2 10.0.22631.0 <10.0.22631.7652
Windows 11 version 26H1 10.0.28000.0 <10.0.28000.3231
Windows Server 2025 10.0.26100.0 <10.0.26100.33650
Windows 11 Version 25H2 10.0.26200.0 <10.0.26200.9711
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

Affected Packages

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_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-359, Exposure of Private Personal Information to an Unauthorized Actor: a component fails to properly restrict access to personal data, allowing a local caller to read it outside its intended trust boundary. Microsoft attributes the issue to an Azure Active Directory component surfaced through the Windows update channel, which is why the MSRC advisory maps to Windows 11 and Windows Server 2025 builds rather than to a cloud service - the affected code ships in the operating system image and is addressed through normal monthly cumulative updates. The CVSS vector CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N is decisive here: AV:L means the vulnerability cannot be triggered across a network or from a remote unauthenticated position, and the scope is unchanged (S:U), so the impact is confined to data accessible on the local host. PR:N/UI:N indicates that once a local execution context exists, no further credentials or victim interaction are required to obtain the disclosure, which is what elevates a low-complexity local bug to a 6.2 score despite the absence of memory-corruption or code-execution primitives. ENISA tracks the same issue under EUVD-2026-99625 with the identical build ranges, corroborating that this is an OS-level fix rather than an Azure AD service-side change.

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Severity by source

NVD PRIMARY 5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
vuln.today AI 6.2 MEDIUM

Local-only reach (AV:L) with no privileges or interaction (PR:N/UI:N) for a user with a local session; high confidentiality of personal data, no integrity or availability impact.

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

Primary rating from NVD.

CVSS VectorNVD

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

Lifecycle Timeline

3
CVSS changed
Oct 16, 2026 - 18:11 NVD
6.2 (MEDIUM) 5.5 (MEDIUM)
Patch available
Oct 13, 2026 - 20:20 EUVD
CVE Published
Oct 13, 2026 - 19:21 cve.org
MEDIUM 6.2

DescriptionNVD

Exposure of private personal information to an unauthorized actor in Azure Active Directory allows an unauthorized attacker to disclose information locally.

Threat Intelligence Overview

EPSS Score
0.5%
Top 62% exploitable
Prevalence
Ubiquitous
affects Windows 11 and Windows Server 2025, deployed in a huge fraction of 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

Attack Technique

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