Skip to main content

Windows RAS EUVDEUVD-2026-100076

| CVE-2026-87698 MEDIUM
Out-of-bounds Read (CWE-125)
2026-10-13 secure@microsoft.com GHSA-qqwm-3m45-9gr3
5.5
CVSS 3.1 · Vendor: microsoft
View

Attack ChainAIDerived

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

  1. Access
    Authenticate to local Windows host
  2. Exploit
    Invoke Remote Access Service Infrastructure
  3. Execution
    Trigger out-of-bounds read
  4. Impact
    Disclose adjacent process memory

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 the attacker to already have a valid low-privilege authenticated session on the target Windows system (PR:L) and local access to it (AV:L) - there is no network-facing or unauthenticated path. The attacker must be able to interact with the Windows Remote Access Service Infrastructure component to supply input that triggers the out-of-bounds read. Limiting factors: the local-only vector means remote exploitation is not possible, exploitation cannot be automated at scale (SSVC Automatable: no), and impact is confined to information disclosure (C:H, I:N, A:N) rather than code execution or system compromise. The affected versions span Windows 10 (1607 through 22H2), Windows 11 (23H2 through 26H2), and Windows Server 2012 through 2025; hosts patched to the fixed builds listed in the EUVD data are not exposed.

Impact

This is a moderate-severity information disclosure vulnerability that is NOT a top-tier emergency priority despite affecting a ubiquitous platform. The CVSS 3.1 base score of 5.5 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N) indicates a local attack vector requiring low privileges and low attack complexity, with high confidentiality impact but no integrity or availability impact - consistent with an out-of-bounds read (CWE-125) that leaks memory rather than enabling code execution. All signals align toward LOW real-world urgency: CISA's SSVC decision framework rates Exploitation as 'none' (no observed or public exploitation), Automatable as 'no' (cannot be reliably scripted at scale, consistent with the local-only vector), and Technical Impact as 'partial.' There is no CISA KEV listing and no EPSS score was provided in the input, so exploitation-probability cannot be quantified here. There is no public exploit identified at time of analysis. The signals are internally consistent - there is no conflict between the local vector, the SSVC 'none/no/partial' rating, and the absence of KEV/POC data - so this reads as a genuine low-to-moderate priority: a patch-in-normal-cycle issue rather than an out-of-band emergency. The main residual risk is as a post-compromise primitive (e.g., leaking memory to defeat ASLR or harvest secrets) for an attacker who already has an authenticated local foothold.

Exploit ScenarioDerived

An attacker who already holds a low-privileged authenticated account on a Windows host (for example via phishing, stolen credentials, or an earlier foothold) locally invokes the Remote Access Service Infrastructure component with crafted input that triggers an out-of-bounds read, causing adjacent process memory to be returned to the attacker. The disclosed memory could contain sensitive data such as credentials, cryptographic material, or address-layout information useful for chaining into a further exploit. No public exploit code has been identified at time of analysis, and the local vector plus low-privilege requirement limit this to attackers with existing access.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.3% exploitation probability (EPSS)

Get an e-mail when this CVE is exploited, patched or re-scored. Free account.

Alert me

AnalysisAIv1 – Oct 14, 2026

An out-of-bounds read in the Windows Remote Access Service Infrastructure lets an attacker who already holds a low-privilege local session on the host read beyond the bounds of an allocated buffer and disclose information from process memory. Exploitation requires both local access (AV:L) and an authenticated low-privilege context (PR:L) per the assessed CVSS vector, with no network-facing or unauthenticated path, and CISA's SSVC assessment marks it non-automatable with only partial technical impact, so this is a moderate-severity disclosure issue rather than a top-tier emergency. No public exploit code has been identified at time of analysis, though the affected component ships across an unusually broad footprint: Windows 10 1607 through 22H2, Windows 11 23H2 through 26H2, and Windows Server 2012 through 2025, including Server Core installations.

RemediationAI

Vendor patches are available, so the primary action is to apply the Microsoft security update for CVE-2026-87698 to every affected build, using the fixed versions enumerated in the advisory: Windows 11 23H2 to 10.0.22631.7652, Windows 11 24H2 and Windows Server 2025 to 10.0.26100.9711 / 10.0.26100.33650 respectively, Windows 11 25H2 to 10.0.26200.9711, Windows 11 26H1 to 10.0.28000.3231, and Windows 11 26H2 to 10.0.26300.9711; Windows 10 1607 to 10.0.14393.9612, Windows 10 1809 and Windows Server 2019 to 10.0.17763.9376, Windows 10 21H2/22H2 to 10.0.19044.7807, Windows Server 2016 to 10.0.14393.9612, Windows Server 2022 to 10.0.20348.5761, Windows Server 2012 to 6.2.9200.26434, and Windows Server 2012 R2 to 6.3.9600.23470. Track the MSRC update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-87698 for the exact KB-to-build mapping and install through your normal patch-management channel, prioritizing internet-exposed VPN/RRAS servers and multi-user hosts where a low-privilege user could reach the RAS stack. Because exploitation is local and requires an existing authenticated session, there is no meaningful network-side workaround (disabling the Remote Access Service or RRAS would break VPN and remote-access functionality for all users and is a disproportionate trade-off for a C:H/I:N/A:N disclosure bug); the realistic compensating controls are therefore host-side hardening - enforce least privilege and remove unnecessary interactive local logon rights so that untrusted users cannot reach the component, restrict who may run code or connect to RAS management interfaces such as the RRAS MMC, and apply Credential Guard / LSASS protections plus RAM-backed storage encryption to reduce the value of any leaked memory (these reduce blast radius but do not fix the flawed bounds check). If an interim measure is genuinely required on a host that cannot be patched, limiting local logon to fully trusted administrators is the least disruptive option, accepting that it does not eliminate the bug for those administrators themselves.

Affected VersionsENISA

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

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

The flaw is classified as CWE-125 (Out-of-bounds Read), meaning the Windows Remote Access Service Infrastructure fails to validate the length or index of an input before dereferencing it, causing the component to read memory past the end (or before the start) of an intended buffer. Because the impact is measured as C:H/I:N/A:N under CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U, the consequence is purely disclosure of memory contents to the triggering caller - no memory corruption, no write primitive, and no integrity or availability effect, and the scope remains unchanged so the read does not escalate across a security boundary by itself. In practice, out-of-bounds reads of this kind can leak adjacent in-process data such as pointers (useful for defeating ASLR in a chained attack), configuration strings, or other resident sensitive material, which is why confidentiality is rated High even at a modest base score. The affected code is the Remote Access Service / Routing and Remote Access stack that is present by default on the listed Windows client and server builds, including Server Core installations; environments on the fixed builds enumerated in the EUVD data are not exposed, so the practical prevalence of this bug is directly tied to patch adoption across a very long-lived set of Windows servicing branches.

Know when the next one hits your stack

  • Watch products and get an email when something new is published
  • Check this CVE against your own stack and servers
  • Exploit and PoC references, threat intelligence from 22 sources

No credit card · 7-day full trial

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 vector and low-privilege authenticated access required (AV:L/PR:L); out-of-bounds read leaks memory giving high confidentiality impact only, with no integrity or availability effect.

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 - 19:21 cve.org
MEDIUM 5.5

DescriptionCVE.org

Out-of-bounds read in Windows Remote Access Service Infrastructure allows an authorized attacker to disclose information locally.

Threat Intelligence Overview

EPSS Score
0.3%
Top 78% exploitable
Prevalence
Ubiquitous
Core Windows client and server component across nearly all 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 0.3%
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.

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy