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Windows Kernel CVE-2026-70249

| EUVDEUVD-2026-99201 HIGH
Use After Free (CWE-416)
2026-10-13 secure@microsoft.com GHSA-hhpq-9qv7-vggj
7.0
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 low-privileged code execution on host
  2. Delivery
    Invoke vulnerable Win32 kernel path
  3. Exploit
    Win race to trigger use-after-free
  4. Execution
    Reclaim freed kernel object
  5. Persist
    Corrupt kernel memory for SYSTEM token
  6. Impact
    Full local 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 the attacker to already have local, interactive or programmatic code-execution ability on the target Windows system at a low privilege level (PR:L) - this is strictly a post-access local privilege-escalation primitive, not a remote entry point (AV:L). No user interaction is needed (UI:N). The primary limiting factor is the high attack complexity (AC:H): the use-after-free (CWE-416) must be triggered by winning a memory-reclamation race in the Win32 kernel subsystem, which demands precise timing and is not reliably repeatable, reducing practical exploitation. Applies to default configurations of the affected Windows client and server builds below the patched versions listed in the EUVD data (e.g., Windows 11 24H2 below 10.0.26100.9711, Server 2022 below 10.0.20348.5761); no special feature or non-default setting is required beyond having a local account.

Impact

This is a genuine but second-tier priority. The CVSS 3.1 vector (AV:L/AC:H/PR:L/UI:N/S:U) scores 7.0 (High) and the signals are internally consistent for a local privilege-escalation bug: exploitation requires local access (AV:L), already-held low privileges (PR:L), and the high attack complexity (AC:H) reflects the race-condition/timing nature typical of a kernel use-after-free (CWE-416). Impact is total on the vulnerable system (C:H/I:H/A:H, scope unchanged), which matches the SSVC 'Technical Impact: total' rating. Critically, the exploitation-risk signals point AWAY from urgency: CISA SSVC lists Exploitation 'none' and Automatable 'no', there is no CISA KEV listing, and no public POC was provided - so there is no public exploit identified at time of analysis. No EPSS score was supplied in the input, so probabilistic exploitation likelihood cannot be quantified. The AC:H and local-only vector further reduce real-world mass-exploitation potential; this is the kind of flaw weaponized as a post-compromise local EoP link in a chain (e.g., after phishing or browser RCE) rather than an internet-facing emergency. Note one metadata tension: the Tags include 'Denial Of Service', but the description and CWE-416 describe privilege elevation, not availability loss - the DoS tag appears to be a generic memory-corruption label rather than the primary impact. Patch-now-on-normal-cycle is the appropriate posture.

Exploit ScenarioDerived

An attacker who already has a low-privileged foothold on a Windows host (via phishing payload, a compromised standard user account, or a browser/sandbox escape) runs a crafted program that triggers the use-after-free in the Win32 kernel subsystem, winning a timing race to reclaim the freed object and corrupt kernel memory. Successful exploitation elevates the process to SYSTEM, giving full control of the machine. No public exploit was identified at time of analysis, and the high attack complexity (AC:H) means reliable exploitation requires precise race-condition timing.

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 – Oct 14, 2026

Local privilege escalation in the Windows Win32 kernel subsystem allows an authenticated attacker who already holds low-privilege code execution on a host to gain SYSTEM-level privileges by triggering a use-after-free (CWE-416) during kernel object reclamation. The weakness is strictly local (AV:L) and high-complexity (AC:H) because the attacker must win a memory-reclamation race, making it a post-access escalation primitive rather than a remote entry point; no public exploit code has been identified at time of analysis (CISA SSVC records Exploitation: none). Every supported Windows 10, Windows 11, and Windows Server build below the fixed revision listed by the vendor is affected, and Microsoft has released patches.

RemediationAI

Primary remediation is to apply the Microsoft security update referenced by MSRC advisory https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-70249 (NVD mirror: https://nvd.nist.gov/vuln/detail/CVE-2026-70249); vendor-released patch is available per vendor advisory, with fixed revisions of 10.0.14393.9612 for Windows 10 1607, Server 2016 and Server 2016 Server Core, 10.0.17763.9376 for Windows 10 1809, Server 2019 and Server 2019 Server Core, 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, 10.0.26200.9711 for Windows 11 25H2, 10.0.28000.3231 for Windows 11 26H1, 10.0.26300.9711 for Windows 11 26H2, 10.0.20348.5761 for Windows Server 2022, and 10.0.26100.33650 for Windows Server 2025 including Server Core; prioritize internet-facing and multi-user hosts where any local account is a potential escalation path. Because this is a local, post-access privilege-escalation primitive rather than a remote vector, compensating controls are about shrinking the local attack surface while patching rolls out: reduce the number of interactive local accounts and remove or disable unused ones (trade-off: administrative overhead and possible disruption to shared-workstation workflows), enforce application allowlisting with WDAC or AppLocker so untrusted binaries cannot execute the race-triggering code path (trade-off: allowlist tuning effort and risk of blocking legitimate line-of-business software), and enable kernel-focused exploit mitigations such as Windows Defender Exploit Guard's kernel pool hardening plus Arbitrary Code Guard and Control Flow Guard on high-value endpoints (trade-off: occasional application compatibility regressions). Restricting interactive logon rights to a minimal set of users and monitoring for anomalous token or process-creation behavior around win32k activity provide detection pressure but do not eliminate an already-present local attacker's ability to attempt the race; none of these controls is a substitute for the vendor patch.

Affected VersionsENISA

Windows Server 2022 10.0.20348.0 <10.0.20348.5761
Windows Server 2019 10.0.17763.0 <10.0.17763.9376
Windows 10 Version 22H2 10.0.19045.0 <10.0.19044.7807
Windows 11 Version 24H2 10.0.26100.0 <10.0.26100.9711
Windows 11 Version 23H2 10.0.22631.0 <10.0.22631.7652
Windows Server 2016 (Server Core installation) 10.0.14393.0 <10.0.14393.9612
Windows 11 Version 26H2 10.0.26300.0 <10.0.26300.9711
Windows Server 2019 (Server Core installation) 10.0.17763.0 <10.0.17763.9376
Windows 11 version 26H1 10.0.28000.0 <10.0.28000.3231
Windows Server 2025 10.0.26100.0 <10.0.26100.33650
Windows 10 Version 1607 10.0.14393.0 <10.0.14393.9612
Windows 10 Version 1809 10.0.17763.0 <10.0.17763.9376
Windows 11 Version 25H2 10.0.26200.0 <10.0.26200.9711
Windows 10 Version 21H2 10.0.19044.0 <10.0.19044.7807
Windows Server 2025 (Server Core installation) 10.0.26100.0 <10.0.26100.33650
Windows Server 2016 10.0.14393.0 <10.0.14393.9612

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_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 16 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 flaw is a use-after-free (CWE-416) in the Win32 kernel subsystem, the kernel-mode component (win32k/win32kbase style surface) that manages windowing, GDI and USER objects on behalf of user-mode processes. A use-after-free arises when a kernel object is freed while a stale pointer or handle reference to it remains reachable; a local attacker who can influence object lifetime can race the allocator so that the freed memory is reallocated under their control, yielding a corrupted or attacker-influenced kernel structure. Because Win32 kernel objects are shared across sessions and tied to token and process-management data, successful corruption typically converts into kernel memory write primitives and ultimately token theft or arbitrary kernel code execution, which is why the assessed vector rates Confidentiality, Integrity and Availability all High (C:H/I:H/A:H) while scope remains Unchanged (S:U). The assessed vector CVSS:3.1/AV:L/AC:H/PR:L/UI:N places exploitation firmly behind an existing foothold: PR:L means the attacker is authenticated with only low privilege, and AC:H reflects the precise timing required to win the reclamation race, which limits reliability and repeatability. The EUVD record confirms the affected surface spans both client and server editions of Windows, all sharing the same Win32 kernel code path, so the same primitive applies to Windows 10, Windows 11 (including the newer 25H2/26H1/26H2 channels) and Windows Server 2016 through 2025.

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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 kernel UAF needs an existing low-priv account (AV:L/PR:L) and a timing race to trigger (AC:H); successful SYSTEM elevation gives total host impact (C:H/I:H/A:H), scope unchanged.

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:N/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
Oct 13, 2026 - 20:20 EUVD
CVE Published
Oct 13, 2026 - 19:19 cve.org
HIGH 7.0

DescriptionCVE.org

Use after free in Windows Win32 Kernel Subsystem allows an authorized attacker to elevate privileges locally.

Executive ViewAI

Why It Matters

A high-severity weakness in the Windows Win32 kernel subsystem allows someone who already has a limited foothold on a machine to escalate to full SYSTEM control, converting a contained intrusion into total control of that host. It cannot be used to break in remotely and requires winning a difficult timing race, so it is an escalation step rather than an entry point, and no public exploit code has been identified at time of analysis. Every Windows 10, Windows 11, and Windows Server build below Microsoft's fixed revision is affected and patches are available, meaning the exposure is manageable but grows with every unpatched endpoint.

Business Impact: Medium
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.3%
Top 79% exploitable
Prevalence
Ubiquitous
Microsoft Windows kernel; present in a huge fraction of 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
Medium
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

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.

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

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