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Attack ChainAIDerived

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

  1. Access
    Gain local user access
  2. Delivery
    Execute code as low-privileged user
  3. Exploit
    Invoke vulnerable QoS Scheduler interface
  4. Execution
    Read restricted kernel data
  5. Impact
    Use disclosed data for lateral movement or privilege escalation

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V14 - Data Protection Data exposure prevention
MITRE ATT&CK

2 techniques across 2 tactics: Collection, Discovery

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 authenticated access with at minimum a standard (low-privileged) user account on the target system - confirmed by CVSS PR:L and AV:L. No network-facing attack surface exists; an attacker must be able to execute code locally, whether through an interactive logon, RDP session, or an already-running local process. No special Windows configuration, specific feature enablement, or non-default setting is identified in the available data as a prerequisite. What limits exploitation: the requirement for pre-existing local code execution eliminates remote unauthenticated attack scenarios entirely; SSVC 'Automatable: no' indicates the attack cannot be scripted for mass exploitation; and the impact is read-only (confidentiality only), so no direct system takeover is possible from this flaw alone.

Impact

The CVSS 3.1 score of 5.5 (Medium) is consistent with a local-only, read-only information disclosure - no integrity or availability impact and no network reachability. The vector AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N indicates low complexity and no user interaction once local access is achieved, but the local attack vector is the primary limiting factor. EPSS at 0.47% (38th percentile) reflects a low probability of exploitation in the wild within 30 days, consistent with SSVC's 'Exploitation: none' and 'Automatable: no' classification. This is not a remote attack surface and is not in CISA KEV. No public exploit code has been identified. In practice, this vulnerability is most dangerous as a post-exploitation tool - an attacker who already has local access could use the information disclosure to stage privilege escalation or exfiltrate network configuration secrets. The partial technical impact rating from SSVC is accurate: this flaw alone does not enable takeover, but the high confidentiality impact rating (C:H) means the exposed data could be highly sensitive.

Exploit ScenarioDerived

An attacker who has obtained a low-privileged shell on a Windows system - through a phishing payload, compromised service account, or RDP brute force - calls into the QoS Packet Scheduler kernel driver via a vulnerable interface to read restricted memory regions or internal data structures. The disclosed information could include network configuration data, credentials cached in kernel memory, or details useful for planning a subsequent privilege escalation. No public exploit code has been identified at 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 – Jul 22, 2026

Information disclosure in the Windows Quality of Service (QoS) Packet Scheduler component exposes sensitive data to locally authenticated low-privileged users across a wide range of Windows client and server releases. The flaw (CWE-200) allows a local attacker with standard user access to read memory or network-related data that should be restricted to higher-privilege contexts. No public exploit exists and SSVC classifies exploitation as none with partial technical impact, but the breadth of affected Windows versions - from Server 2012 through Windows 11 26H1 and Server 2025 - makes patching a broad operational priority.

RemediationAI

Apply the vendor-released patch via Windows Update or WSUS targeting the fixed builds listed per platform: Windows 10 1607 and Server 2016 to build 10.0.14393.9339 or later; Windows 10 1809 and Server 2019 to 10.0.17763.9020 or later; Windows 10 21H2 to 10.0.19044.7548 or later; Windows 10 22H2 to 10.0.19045.7548 or later; Windows 11 24H2 to 10.0.26100.8875 or later; Server 2025 to 10.0.26100.33158 or later; Windows 11 25H2 to 10.0.26200.8875 or later; Windows 11 26H1 to 10.0.28000.2269 or later; Server 2022 to 10.0.20348.5386 or later; Server 2012 to 6.2.9200.26226 or later; and Server 2012 R2 to 6.3.9600.23291 or later. The advisory is published at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50431. Where immediate patching is not possible, restrict interactive and remote desktop logon rights to the minimum necessary set of users on affected systems, as the attack requires local authenticated access. Note that disabling the QoS Packet Scheduler entirely may impact network traffic prioritization for applications relying on DSCP tagging.

Affected VersionsENISA

Windows Server 2012 (Server Core installation) 6.2.9200.0 <6.2.9200.26226
Windows Server 2019 (Server Core installation) 10.0.17763.0 <10.0.17763.9020
Windows 10 Version 1809 10.0.17763.0 <10.0.17763.9020
Windows 10 Version 1607 10.0.14393.0 <10.0.14393.9339
Windows Server 2022 10.0.20348.0 <10.0.20348.5386
Windows Server 2025 (Server Core installation) 10.0.26100.0 <10.0.26100.33158
Windows Server 2019 10.0.17763.0 <10.0.17763.9020
Windows Server 2012 R2 (Server Core installation) 6.3.9600.0 <6.3.9600.23291
Windows 10 Version 21H2 10.0.19044.0 <10.0.19044.7548
Windows 11 Version 25H2 10.0.26200.0 <10.0.26200.8875
Windows 10 Version 22H2 10.0.19045.0 <10.0.19045.7548
Windows Server 2016 (Server Core installation) 10.0.14393.0 <10.0.14393.9339
Windows 11 version 26H1 10.0.28000.0 <10.0.28000.2269
Windows Server 2012 R2 6.3.9600.0 <6.3.9600.23291
Windows Server 2025 10.0.26100.0 <10.0.26100.33158
Windows Server 2016 10.0.14393.0 <10.0.14393.9339
Windows Server 2012 6.2.9200.0 <6.2.9200.26226
Windows 11 Version 24H2 10.0.26100.0 <10.0.26100.8875

Affected Packages

microsoft windows_10_version_1607_10_0_14393_9339 fix: Windows 10 Version 1607 for 32-bit Systems 10.0.14393.9339, Windows 10 Version 1607 for x64-based Systems 10.0.14393.9339
microsoft windows_10_version_1809_10_0_17763_9020 fix: Windows 10 Version 1809 for 32-bit Systems 10.0.17763.9020, Windows 10 Version 1809 for x64-based Systems 10.0.17763.9020
microsoft windows_10_version_21h2_10_0_19044_7548 fix: Windows 10 Version 21H2 for 32-bit Systems 10.0.19044.7548, Windows 10 Version 21H2 for ARM64-based Systems 10.0.19044.7548, Windows 10 Version 21H2 for x64-based Systems 10.0.19044.7548
microsoft windows_10_version_22h2_10_0_19045_7548 fix: Windows 10 Version 22H2 for 32-bit Systems 10.0.19045.7548, Windows 10 Version 22H2 for ARM64-based Systems 10.0.19045.7548, Windows 10 Version 22H2 for x64-based Systems 10.0.19045.7548
microsoft windows_11_version_24h2_10_0_26100_8875 fix: Windows 11 Version 24H2 for ARM64-based Systems 10.0.26100.8875, Windows 11 Version 24H2 for x64-based Systems 10.0.26100.8875
microsoft windows_11_version_25h2_10_0_26200_8875 fix: Windows 11 Version 25H2 for ARM64-based Systems 10.0.26200.8875, Windows 11 Version 25H2 for x64-based Systems 10.0.26200.8875
microsoft windows_11_version_26h1_10_0_28000_2269 fix: Windows 11 version 26H1 for x64-based Systems 10.0.28000.2269
microsoft windows_11_version_26h1_10_0_28000_2525 fix: Windows 11 Version 26H1 for ARM64-based Systems 10.0.28000.2525
microsoft windows_server_2012_6_2_9200_26226 fix: Windows Server 2012 6.2.9200.26226, Windows Server 2012 (Server Core installation) 6.2.9200.26226
microsoft windows_server_2012_r2_6_3_9600_23291 fix: Windows Server 2012 R2 6.3.9600.23291, Windows Server 2012 R2 (Server Core installation) 6.3.9600.23291
microsoft windows_server_2016_10_0_14393_9339 fix: Windows Server 2016 10.0.14393.9339, Windows Server 2016 (Server Core installation) 10.0.14393.9339
microsoft windows_server_2019_10_0_17763_9020 fix: Windows Server 2019 10.0.17763.9020, Windows Server 2019 (Server Core installation) 10.0.17763.9020
microsoft windows_server_2022_10_0_20348_5386 fix: Windows Server 2022 10.0.20348.5386
microsoft windows_server_2025_10_0_26100_33158 fix: Windows Server 2025 10.0.26100.33158, Windows Server 2025 (Server Core installation) 10.0.26100.33158
euvd windows_10_version_1607 fix: 10.0.14393.9339
euvd windows_10_version_1809 fix: 10.0.17763.9020
euvd windows_10_version_21h2 fix: 10.0.19044.7548
euvd windows_10_version_22h2 fix: 10.0.19045.7548
euvd windows_11_version_24h2 fix: 10.0.26100.8875
euvd windows_11_version_25h2 fix: 10.0.26200.8875
euvd windows_11_version_26h1 fix: 10.0.28000.2269
euvd windows_server_2012 fix: 6.2.9200.26226
euvd windows_server_2012_r2 fix: 6.3.9600.23291
euvd windows_server_2012_r2_server_core_installation fix: 6.3.9600.23291
euvd windows_server_2012_server_core_installation fix: 6.2.9200.26226
euvd windows_server_2016 fix: 10.0.14393.9339
euvd windows_server_2016_server_core_installation fix: 10.0.14393.9339
euvd windows_server_2019 fix: 10.0.17763.9020
euvd windows_server_2019_server_core_installation fix: 10.0.17763.9020
euvd windows_server_2022 fix: 10.0.20348.5386
euvd windows_server_2025 fix: 10.0.26100.33158
euvd windows_server_2025_server_core_installation fix: 10.0.26100.33158

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 32 packages in microsoft, euvd

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

Technical ContextAI · show details

The Windows QoS Packet Scheduler (pacer.sys) is a kernel-mode driver responsible for managing network traffic prioritization and bandwidth allocation on Windows systems. CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor) indicates that the scheduler fails to properly restrict what data a low-privileged caller can access, likely via an improperly validated IOCTL interface or insufficient access control on kernel objects exposed to user-mode. CPE data confirms the flaw is present across the entire modern Windows product line: Windows 10 versions 1607 through 22H2, Windows 11 versions 24H2 through 26H1, and Windows Server 2012 through Server 2025. The CVSS local attack vector (AV:L) confirms that exploitation occurs through local process interaction with the kernel driver rather than over a network.

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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
CIRCL (temporal) 4.8 MEDIUM
vuln.today AI 5.5 MEDIUM

Local attack vector and low privileges confirmed; high confidentiality impact from kernel data read; no integrity or availability impact.

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

DescriptionCVE.org

Windows Quality of Service (QoS) Packet Scheduler Information Disclosure Vulnerability

Threat Intelligence Overview

EPSS Score
0.5%
Top 62% exploitable
Prevalence
Ubiquitous
Windows deployed in virtually all enterprise environments globally
Vendor Action
See Below
Required. The vulnerability documented by this CVE requires customer action to resolve.
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 0.5%
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
Scheduled
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact· derived
High
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

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

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