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Windows Remote Access CVE-2026-65672

| EUVDEUVD-2026-56436 HIGH
Heap-based Buffer Overflow (CWE-122)
2026-08-11 secure@microsoft.com GHSA-mj96-gpjc-hg8j
7.8
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
    Gain local user session
  2. Delivery
    Craft malformed Remote Access API call
  3. Exploit
    Trigger heap buffer overflow
  4. Execution
    Corrupt heap metadata
  5. Persist
    Redirect execution to controlled payload
  6. Impact
    Execute code as SYSTEM

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Heap buffer bounds checking
MITRE ATT&CK

1 technique across 1 tactic: Execution

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

Exploitation Conditions

Exploitation requires an authenticated local session on the target host with at minimum standard (low-privilege) user rights, as confirmed by the CVSS vector PR:L. No special product feature, non-default configuration, or specific network protocol needs to be enabled beyond the presence of the Windows Remote Access API component, which is present by default on all affected Windows 11 and Windows Server editions. There is no network-facing attack surface for this vulnerability (AV:L); an attacker must already have local code execution. Exploitation is limited by the requirement for physical or remote local access (e.g., RDP session, terminal server, existing malware foothold). No user interaction is required once local access is established.

Impact

The CVSS 3.1 score of 7.8 reflects a high-severity local privilege escalation with low attack complexity, making it a reliable escalation primitive for any attacker who has already obtained local access to an affected host. The unchanged scope (S:U) bounds the immediate blast radius to the compromised system, but full C:H/I:H/A:H impact means total host compromise is achievable. No EPSS data was included in the available intelligence, limiting probabilistic exploitation forecasting - this is a notable gap. KEV listing is absent and no public proof-of-concept has been identified, which distinguishes this from imminently weaponized threats; however, the low attack complexity means that once any researcher or threat actor develops a working exploit, deployment in post-intrusion toolkits is straightforward. The broad affected surface - multiple Windows 11 release trains plus Windows Server 2022 and 2025 - means this is relevant across virtually all modern Windows enterprise environments, and teams should prioritize patching within standard patch cycle SLAs rather than treating it as deferred. The absence of a KEV listing should not be read as confirmation of safety; it reflects only that mass exploitation has not yet been publicly confirmed.

Exploit ScenarioDerived

An attacker who has obtained a low-privileged local session on a vulnerable Windows host - for example, through phishing a standard user, exploiting a remote code execution vulnerability, or abusing a misconfigured service - calls the Windows Remote Access API with a specially crafted input that triggers the heap buffer overflow. By corrupting heap structures, the attacker redirects execution to controlled code running as SYSTEM, achieving full local privilege escalation with no additional user interaction required. No public proof-of-concept has been identified at time of analysis, but the AC:L rating indicates the exploitation path is not technically complex.

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 – Aug 11, 2026

Privilege escalation in the Windows Remote Access API via a heap-based buffer overflow (CWE-122) allows an authenticated local attacker with low privileges to gain full SYSTEM-level control over affected Windows 11 and Windows Server 2022/2025 hosts. The CVSS vector (AV:L/AC:L/PR:L/UI:N) confirms exploitation requires only a valid local account and no user interaction, making it a reliable post-compromise escalation path. No public exploit code or CISA KEV listing has been identified at time of analysis; Microsoft has released patches for all enumerated affected versions.

RemediationAI

The primary fix is to apply the Microsoft security update that advances affected builds to or beyond their respective fix thresholds: Windows 11 23H2 to build 10.0.22631.7517 or later, Windows 11 24H2 to 10.0.26100.9168 or later, Windows 11 25H2 to 10.0.26200.9168 or later, Windows 11 26H1 to 10.0.28000.2704 or later, Windows Server 2025 (including Server Core) to 10.0.26100.33296 or later, and Windows Server 2022 to 10.0.20348.5499 or later. Updates should be obtained via Windows Update, WSUS, or Microsoft Update Catalog per the advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-65672. Where immediate patching is not feasible, limiting interactive local logon rights to only trusted administrative accounts reduces the attacker pool, though this does not eliminate the vulnerability since PR:L means any standard user account is sufficient. Restricting use of Remote Access API features via application control policies (AppLocker or WDAC) for non-administrative users may further reduce exposure, with the trade-off of potentially disrupting VPN client functionality for standard users.

Affected VersionsENISA

Windows 11 Version 23H2 10.0.22631.0 <10.0.22631.7517
Windows 11 version 26H1 10.0.28000.0 <10.0.28000.2704
Windows 11 Version 25H2 10.0.26200.0 <10.0.26200.9168
Windows Server 2025 10.0.26100.0 <10.0.26100.33296
Windows Server 2025 (Server Core installation) 10.0.26100.0 <10.0.26100.33296
Windows 11 Version 24H2 10.0.26100.0 <10.0.26100.9168
Windows Server 2022 10.0.20348.0 <10.0.20348.5499

Affected Packages

euvd windows_11_version_23h2 fix: 10.0.22631.7517
euvd windows_11_version_24h2 fix: 10.0.26100.9168
euvd windows_11_version_25h2 fix: 10.0.26200.9168
euvd windows_11_version_26h1 fix: 10.0.28000.2704
euvd windows_server_2022 fix: 10.0.20348.5499
euvd windows_server_2025 fix: 10.0.26100.33296
euvd windows_server_2025_server_core_installation fix: 10.0.26100.33296

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 Windows Remote Access API (RASAPI32) is a core Windows subsystem providing the programming interface for applications to establish and manage remote network connections, including VPN tunnels and dial-up sessions. CWE-122 (Heap-based Buffer Overflow) identifies the root cause: a write operation exceeds the bounds of a heap-allocated buffer within this API, enabling corruption of adjacent heap metadata. On Windows heap implementations, such corruption can be leveraged to redirect execution flow, overwrite function pointers, or manipulate security-sensitive structures. The CVSS vector AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H is consistent with an API-layer flaw exploitable by any authenticated user via a crafted API call, with no complexity barriers or prerequisite configurations beyond holding a local logon. Affected CPE-equivalent targets span Windows 11 versions 23H2 through 26H1 and Windows Server 2022 and 2025 per EUVD-2026-56436.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (microsoft) PRIMARY 7.8 HIGH
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
ENISA EUVD HIGH
vuln.today AI 7.8 HIGH

Local-only attack vector with no configuration prerequisites; low-privilege authenticated session sufficient; full system compromise achievable post-exploit.

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.0 AV:L/AC:L/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
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

2
Patch available
Aug 11, 2026 - 18:19 EUVD
CVE Published
Aug 11, 2026 - 17:18 nvd
HIGH 7.8

DescriptionCVE.org

Heap-based buffer overflow in Windows Remote Access API allows an authorized attacker to elevate privileges locally.

Executive ViewAI

Why It Matters

A privilege escalation vulnerability in Windows Remote Access API affects Windows 11, Windows Server 2022, and Windows Server 2025, enabling authenticated local users with low privileges to gain complete administrative control and compromise system security. This creates immediate risk across enterprise deployments, as any employee or service account with basic local access can escalate to SYSTEM-level permissions, threatening data confidentiality and operational integrity. Organizations must treat this as a priority patch for any infrastructure running these widely deployed operating systems.

Business Impact: High
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.3%
Top 82% exploitable
Prevalence
Ubiquitous
Windows 11 and Server 2022/2025 dominate modern enterprise desktop and server deployments globally.
Threat Intel
1
1 sources
Vendor Status
Publicly Disclosed:No
Exploited:No
Latest Software Release:Exploitation Less Likely
Data Quality
6 sources
Confidence: High

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

Priority Score

44
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +39
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: +5

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.

A heap overflow occurs when a program writes data beyond the bounds of a buffer allocated in the heap memory region.

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