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Windows Server KDC CVE-2026-69712

| EUVDEUVD-2026-73070 HIGH
Use After Free (CWE-416)
2026-09-08 secure@microsoft.com GHSA-g8f7-gpw2-vw93
8.8
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
    Obtain low-privileged domain credentials
  2. Delivery
    Reach domain controller port 88 over network
  3. Exploit
    Send crafted Kerberos request triggering use-after-free
  4. Execution
    Corrupt KDC process memory
  5. Persist
    Execute arbitrary code as privileged service
  6. Impact
    Fully compromise Active Directory domain

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

The attacker must hold a valid low-privileged Active Directory domain account (PR:L per CVSS) and have network connectivity to TCP/UDP port 88 on a Windows Server domain controller running the KDC service. No special configuration is required beyond a standard Active Directory domain deployment - KDC is enabled by default on every domain controller and cannot be disabled without breaking domain authentication. Exploitation is limited to principals that can authenticate to the domain; unauthenticated external attackers cannot reach the vulnerable code path without valid credentials. Exploitation complexity is low (AC:L), and no user interaction is needed from any administrator or victim.

Impact

CVSS 8.8 (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) accurately reflects a high-severity network-exploitable flaw requiring only low privileges. The low attack complexity and absence of user-interaction requirements mean that any authenticated domain user - including service accounts or accounts with minimal rights - could attempt exploitation from any network-accessible position reaching TCP/UDP port 88 on a domain controller. Domain controllers are critical infrastructure; code execution on a DC effectively means full Active Directory compromise, so the C:H/I:H/A:H impact ratings are well-grounded. No EPSS data was provided in the input, so exploitation probability cannot be quantified; the absence of KEV listing and public POC lowers immediate urgency marginally, but the low barrier (PR:L, AC:L) means any mid-sized enterprise network exposing KDC to authenticated users - which is by definition every Active Directory deployment - should treat patching as urgent. The 'Denial of Service' tag in the input metadata understates the actual impact: the CVSS triple-H and the description both confirm code execution, not merely availability loss.

Exploit ScenarioDerived

An attacker with any valid low-privileged domain account (e.g., a standard user account or a compromised service account) sends a specially crafted Kerberos authentication request over the network to port 88 on a domain controller, triggering the use-after-free condition in the KDC request-handling path. Successful exploitation results in arbitrary code execution in the context of the KDC service process, which runs with high privileges on domain controllers, enabling full Active Directory compromise. No public exploit code is identified at time of analysis, but the low complexity and low privilege barrier make this an attractive target for post-authentication lateral movement.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.9% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 09, 2026

Remote code execution in the Windows Key Distribution Center (KDC) - the Kerberos authentication service running on every Active Directory domain controller - allows a low-privileged authenticated network attacker to execute arbitrary code via a use-after-free memory corruption flaw (CWE-416). Every currently-supported Windows Server release from Server 2012 through Server 2025 is affected, spanning the full breadth of enterprise Active Directory infrastructure. Microsoft has released patches with exact build-level thresholds per platform; no public exploit code and no CISA KEV listing are identified at time of analysis.

RemediationAI

Apply the Microsoft Security Update for each affected platform to meet or exceed the minimum patched build: Server 2012 ≥6.2.9200.26349, Server 2012 R2 ≥6.3.9600.23397, Server 2016 ≥10.0.14393.9512, Server 2019 ≥10.0.17763.9245, Server 2022 ≥10.0.20348.5622, Server 2025 ≥10.0.26100.33438. Full advisory and update package links are available at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69712. For environments where immediate patching of domain controllers is not feasible, restrict network access to port 88 (TCP and UDP) on domain controllers to trusted management subnets and authenticated client VLAN segments only using perimeter or host-based firewall rules; note that this will not prevent exploitation by any already-on-network authenticated principal and will cause Kerberos authentication failures for hosts outside the permitted subnets, so plan the ACL scope carefully. There is no documented feature-level workaround for the KDC itself - patching is the definitive fix.

Affected VersionsENISA

Windows Server 2012 R2 6.3.9600.0 <6.3.9600.23397
Windows Server 2016 (Server Core installation) 10.0.14393.0 <10.0.14393.9512
Windows Server 2025 10.0.26100.0 <10.0.26100.33438
Windows Server 2019 10.0.17763.0 <10.0.17763.9245
Windows Server 2012 R2 (Server Core installation) 6.3.9600.0 <6.3.9600.23397
Windows Server 2025 (Server Core installation) 10.0.26100.0 <10.0.26100.33438
Windows Server 2012 (Server Core installation) 6.2.9200.0 <6.2.9200.26349
Windows Server 2019 (Server Core installation) 10.0.17763.0 <10.0.17763.9245
Windows Server 2016 10.0.14393.0 <10.0.14393.9512
Windows Server 2012 6.2.9200.0 <6.2.9200.26349
Windows Server 2022 10.0.20348.0 <10.0.20348.5622

Affected Packages

euvd windows_server_2012 fix: 6.2.9200.26349
euvd windows_server_2012_r2 fix: 6.3.9600.23397
euvd windows_server_2012_r2_server_core_installation fix: 6.3.9600.23397
euvd windows_server_2012_server_core_installation fix: 6.2.9200.26349
euvd windows_server_2016 fix: 10.0.14393.9512
euvd windows_server_2016_server_core_installation fix: 10.0.14393.9512
euvd windows_server_2019 fix: 10.0.17763.9245
euvd windows_server_2019_server_core_installation fix: 10.0.17763.9245
euvd windows_server_2022 fix: 10.0.20348.5622
euvd windows_server_2025 fix: 10.0.26100.33438
euvd windows_server_2025_server_core_installation fix: 10.0.26100.33438

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 11 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 KDC implements the Kerberos v5 authentication protocol (RFC 4120) and runs as a core service (kdcsvc.dll) on Active Directory Domain Controllers, typically listening on TCP/UDP port 88. CWE-416 (Use After Free) occurs when code references memory that has already been deallocated; in network-facing request processing paths this can be triggered remotely without requiring physical access. The EUVD-supplied affected version ranges confirm the flaw is present in kdc-related components across Windows Server 2012 (NT 6.2), 2012 R2 (NT 6.3), 2016, 2019, 2022, and 2025, covering both full and Server Core installation types. Because the KDC operates within the lsass.exe or a dedicated service context on domain controllers, successful exploitation carries extremely high post-compromise value.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (microsoft) PRIMARY 8.8 HIGH
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vuln.today AI 8.8 HIGH

Network-reachable KDC requires only a valid domain account (PR:L); no configuration prerequisite beyond standard AD; code execution yields full C/I/A impact.

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

Lifecycle Timeline

2
Patch available
Sep 08, 2026 - 18:35 EUVD
CVE Published
Sep 08, 2026 - 18:19 nvd
HIGH 8.8

DescriptionCVE.org

Use after free in Windows Key Distribution Center allows an authorized attacker to execute code over a network.

Executive ViewAI

Why It Matters

A critical vulnerability in Active Directory domain controllers (Windows Server 2012-2025) allows any domain user to gain complete control of the organization's identity infrastructure through remote code execution. No public exploit identified at time of analysis. Domain controller compromise puts every system, user account, and credential in the enterprise at risk, as controllers are the foundation of all Windows authentication and access control. Immediate patching across all domain controllers is essential to prevent potential takeover of the organization's entire IT infrastructure.

Business Impact: Severe
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.9%
Top 43% exploitable
Prevalence
High
Active Directory KDC on domain controllers in virtually every enterprise
Threat Intel
1
1 sources
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 HIGH
CISA KEV No
Public POC No
EPSS 0.9%
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
Open
Automatable
No
Human Impact
Very High
Technical Impact
Total

Priority Score

45
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +44
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.

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