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Windows iSCSI CVE-2026-69721

| EUVDEUVD-2026-99275 MEDIUM
Out-of-bounds Read (CWE-125)
2026-10-13 secure@microsoft.com GHSA-6rfp-qpg7-x22m
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
    Authenticate to local Windows host
  2. Exploit
    Invoke affected iSCSI driver path
  3. Execution
    Trigger out-of-bounds read
  4. Impact
    Disclose adjacent memory contents

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, read limits
MITRE ATT&CK

1 technique across 1 tactic: Collection

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires local access with valid low-privileged credentials on the affected Windows host (PR:L, AV:L) - it cannot be triggered remotely or by an unauthenticated user, and no user interaction of a victim is needed (UI:N). The attacker must reach the vulnerable Windows iSCSI code path; the description does not specify whether the iSCSI Initiator service must be running or specially configured, so verify whether the iSCSI feature must be active on the target. The limiting factors - required prior authentication, local-only vector, and confidentiality-only impact (no code execution or integrity/availability loss by itself) - mean realistic risk is primarily as a memory-disclosure primitive chained into other local attacks rather than standalone compromise.

Impact

This is a moderate-priority, low-urgency issue. The CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N, base 5.5) describes a locally exploitable out-of-bounds read requiring an already-authenticated low-privileged attacker on the host; it yields high confidentiality impact (memory disclosure) but no integrity or availability impact. There is no CISA KEV listing and no public exploit identified at time of analysis, so this is 'no public exploit identified at time of analysis' rather than active exploitation. No EPSS score and no SSVC decision data were supplied, so automatability and exploitation-status signals from those frameworks cannot be evaluated - this absence is noted, not treated as low risk by default. Signals are internally consistent: the local attack vector, required privileges, and information-disclosure-only impact all point to a secondary/chaining bug (e.g., defeating ASLR or leaking sensitive kernel/driver memory) rather than a standalone critical. Net: patch on normal Patch-Tuesday cadence; it is not a high-real-risk emergency given local access is a prerequisite and no exploitation or POC is evidenced.

Exploit ScenarioDerived

A low-privileged user already logged into a Windows host (or malware running in a low-integrity context) invokes an affected iSCSI driver code path with crafted input, triggering an out-of-bounds read that returns adjacent memory contents. The leaked data could include kernel pointers or secrets usable to bypass ASLR or stage a further local privilege-escalation chain. No public exploit code is identified, and the local-only vector with required authentication limits this to attackers who already have a foothold.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.4% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 13, 2026

An out-of-bounds read (CWE-125) in the Windows iSCSI component allows a locally authenticated, low-privileged attacker to disclose sensitive memory contents from the affected host, rated CVSS 5.5 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N). Exploitation is strictly local: the attacker must already hold valid low-privileged credentials on the machine and reach the vulnerable iSCSI code path - no remote or unauthenticated vector and no victim interaction are involved, and the impact is confidentiality-only, with no code execution, integrity, or availability loss on its own. Vendor-released patches are available through Microsoft's MSRC update guide, and no public exploit code or confirmed active exploitation (CISA KEV) has been identified at time of analysis; the primary risk is as a memory-disclosure/ASLR-bypass primitive chained into a larger local attack rather than a standalone compromise.

RemediationAI

Apply the vendor fix: Microsoft has released patches for this issue through the MSRC update guide (https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69721) - install the current cumulative update for your branch so the target build meets or exceeds the EUVD remediation thresholds, for example 10.0.14393.9612 for Windows 10 1607/Server 2016, 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, 10.0.26100.33650 for Server 2025, 10.0.20348.5761 for Server 2022, 6.2.9200.26434 for Server 2012 and 6.3.9600.23470 for Server 2012 R2; verify the exact per-build threshold in the advisory before treating a host as remediated. Prioritise servers and workstations that actually use iSCSI storage, since the vulnerable component may only be reachable on hosts with the feature active. Where patching must be deferred, the most effective compensating controls follow directly from the local, authenticated prerequisite: reduce the number of accounts with interactive or service logon rights on iSCSI-enabled hosts (removing low-privileged local footholds removes the PR:L prerequisite, at the cost of day-to-day administrative convenience), and stop or disable the iSCSI Initiator service (MSiSCSI) on hosts where iSCSI storage is not required, accepting that this breaks any existing iSCSI-attached volumes. Blocking or filtering TCP 3260 outbound limits target-side attack surface but does not mitigate this local vector. Because the flaw yields only information disclosure, treat any detected use as a probable precursor to a larger local exploit chain, and monitor for anomalous local processes reading the iSCSI stack or repeated crashes/diagnostics in the storage path that could indicate probing. No public exploit code and no confirmed active exploitation (CISA KEV) were identified at time of analysis, so remediation can be scheduled within normal patch cycles rather than treated as an emergency, consistent with a moderate-priority, low-urgency rating.

Affected VersionsENISA

Windows Server 2016 (Server Core installation) 10.0.14393.0 <10.0.14393.9612
Windows Server 2012 R2 6.3.9600.0 <6.3.9600.23470
Windows Server 2012 6.2.9200.0 <6.2.9200.26434
Windows Server 2022 10.0.20348.0 <10.0.20348.5761
Windows Server 2016 10.0.14393.0 <10.0.14393.9612
Windows Server 2012 R2 (Server Core installation) 6.3.9600.0 <6.3.9600.23470
Windows 11 Version 26H2 10.0.26300.0 <10.0.26300.9711
Windows 10 Version 1607 10.0.14393.0 <10.0.14393.9612
Windows Server 2019 (Server Core installation) 10.0.17763.0 <10.0.17763.9376
Windows Server 2025 (Server Core installation) 10.0.26100.0 <10.0.26100.33650
Windows 11 version 26H1 10.0.28000.0 <10.0.28000.3231
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 2019 10.0.17763.0 <10.0.17763.9376
Windows Server 2025 10.0.26100.0 <10.0.26100.33650
Windows 11 Version 23H2 10.0.22631.0 <10.0.22631.7652
Windows Server 2012 (Server Core installation) 6.2.9200.0 <6.2.9200.26434
Windows 10 Version 22H2 10.0.19045.0 <10.0.19044.7807
Windows 10 Version 21H2 10.0.19044.0 <10.0.19044.7807
Windows 10 Version 1809 10.0.17763.0 <10.0.17763.9376

Affected Packages

euvd windows_10_version_1607 fix: 10.0.14393.9612
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_2012 fix: 6.2.9200.26434
euvd windows_server_2012_r2 fix: 6.3.9600.23470
euvd windows_server_2012_r2_server_core_installation fix: 6.3.9600.23470
euvd windows_server_2012_server_core_installation fix: 6.2.9200.26434
euvd windows_server_2016 fix: 10.0.14393.9612
euvd windows_server_2016_server_core_installation fix: 10.0.14393.9612
euvd windows_server_2019 fix: 10.0.17763.9376
euvd windows_server_2019_server_core_installation fix: 10.0.17763.9376
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 20 packages in euvd

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

Technical ContextAI · show details

iSCSI is the transport that carries SCSI commands and data over TCP/IP, implemented in Windows by the iSCSI Initiator service (MSiSCSI) and its associated kernel-mode driver stack, which parse iSCSI PDUs, login/negotiation parameters, and SCSI command blocks exchanged with targets on port 3260. CWE-125 (Out-of-bounds Read) means the component fails to validate a length, offset, or index before reading from a buffer - in this case while processing iSCSI structures - so the process reads memory beyond the intended object and can return it to the caller, leaking kernel or heap contents such as pointers and pool metadata. The assessed vector AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N confirms the flaw is reachable only from the local machine by an attacker with low privileges, requires no user interaction, and affects only confidentiality, giving high confidentiality impact without scope change. Because the disclosure is memory contents rather than code execution, its practical value is typically as an information-leak building block (for example to defeat ASLR or map kernel layout) in a multi-stage local exploit chain; the available description does not state whether the iSCSI Initiator service must be running or specifically configured for the vulnerable path to be reachable.

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  • Exploit and PoC references, threat intelligence from 22 sources

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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 authenticated attacker (AV:L/PR:L) triggers an out-of-bounds read with no reliability barriers (AC:L); impact is memory disclosure only, so C:H and I:N/A:N.

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 - 19:18 cve.org
MEDIUM 5.5

DescriptionCVE.org

Out-of-bounds read in Windows iSCSI allows an authorized attacker to disclose information locally.

Threat Intelligence Overview

EPSS Score
0.4%
Top 66% exploitable
Prevalence
Ubiquitous
Windows OS component spanning client and server, present in most environments
Vendor Status
Publicly Disclosed:No
Exploited:No
Latest Software Release:Exploitation Unlikely
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 0.4%
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

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

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