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Attack ChainAIDerived

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

  1. Access
    Obtain low-privilege domain credentials
  2. Delivery
    Connect to target over network
  3. Exploit
    Send crafted Kerberos authentication request
  4. Execution
    Trigger null pointer dereference in Kerberos handler
  5. Persist
    Crash Kerberos service
  6. Impact
    Deny authentication to dependent users

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A10:2025 - Mishandling of Exceptional Conditions
ASVS 5.0
V16 - Security Logging and Error Handling Null pointer safety, defensive checks
MITRE ATT&CK

1 technique across 1 tactic: Impact

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 attacker to hold at minimum a low-privilege authenticated credential within the target domain or network environment (PR:L per CVSS vector). The attacker must have network access to reach the target system on Kerberos service ports (typically TCP/UDP 88). No user interaction is required (UI:N). Exploitation is fundamentally limited by the authentication prerequisite: unauthenticated external attackers cannot directly exploit this vulnerability without first obtaining valid credentials. No specific non-default configuration or feature enablement is indicated as required by the available description - the vulnerability appears present in the standard Kerberos authentication path. The scope is unchanged (S:U), meaning a successful exploit does not allow the attacker to pivot beyond the availability impact on the targeted component.

Impact

The CVSS 6.5 Medium score reflects genuine but bounded risk. The network attack vector (AV:N) with low complexity (AC:L) and no user interaction (UI:N) makes the vulnerability easy to trigger remotely, but the low-privileges requirement (PR:L) is a meaningful limiting factor - the attacker must hold a valid domain credential. The impact is exclusively availability (A:H, C:N, I:N), meaning no data is exposed and no integrity violations occur; the worst outcome is a service or system crash. No EPSS score was provided, so exploitation probability cannot be quantified probabilistically. The absence of a CISA KEV listing and lack of identified POC code indicate this is not currently under active widespread exploitation. Real-world priority is moderate: relevant primarily to environments where authenticated internal users or compromised accounts present a threat model, particularly against Domain Controllers where Kerberos service disruption would cascade into authentication outages across the domain. It is not a critical internet-facing risk due to the authentication prerequisite.

Exploit ScenarioDerived

An authenticated domain user - or an attacker who has compromised any low-privilege domain account - sends a specially crafted Kerberos authentication request over the network to a target Windows server or Domain Controller. The malformed request triggers a null pointer dereference in the Windows Kerberos implementation, causing the Kerberos service to crash and rendering authentication services unavailable. No public exploit code has been identified at time of analysis, but the low attack complexity (AC:L) suggests exploitation would be straightforward once a triggering request structure is identified.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Jun 09, 2026

Null pointer dereference in Windows Kerberos enables an authenticated network attacker to crash the Kerberos service, causing denial of service. The CVSS vector (AV:N/AC:L/PR:L/UI:N) confirms exploitation is achievable over the network by any low-privilege authenticated user with no user interaction required, resulting in high availability impact (A:H) with no confidentiality or integrity consequences. No active exploitation confirmed (not in CISA KEV), and no public exploit code has been identified at time of analysis.

RemediationAI

Apply the Microsoft security update detailed in the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42903. Exact patch version numbers are not confirmed from the available data and must be verified directly via that advisory - do not rely on inferred version numbers. As a compensating control prior to patching, restrict access to Kerberos service ports (TCP/UDP 88) using network segmentation or host-based firewall rules to limit exposure to trusted network segments and authenticated endpoints only; note this trade-off may disrupt legitimate cross-segment authentication. Additionally, monitor Domain Controllers for anomalous Kerberos service crashes or authentication failures, which may indicate active exploitation attempts. For environments where immediate patching is not possible, consider limiting which accounts can initiate Kerberos authentication requests from untrusted segments, though this may impact normal domain operations.

Affected VersionsENISA

Windows 11 Version 23H2 10.0.22631.0 <10.0.22631.7219
Windows 10 Version 1809 10.0.17763.0 <10.0.17763.8880
Windows 11 Version 24H2 10.0.26100.0 <10.0.26100.8655
Windows Server 2016 (Server Core installation) 10.0.14393.0 <10.0.14393.9234
Windows 11 Version 25H2 10.0.26200.0 <10.0.26200.8655
Windows Server 2016 10.0.14393.0 <10.0.14393.9234
Windows 10 Version 22H2 10.0.19045.0 <10.0.19045.7417
Windows Server 2025 (Server Core installation) 10.0.26100.0 <10.0.26100.32995
Windows 10 Version 21H2 10.0.19044.0 <10.0.19044.7417
Windows Server 2022 10.0.20348.0 <10.0.20348.5256
Windows Server 2019 10.0.17763.0 <10.0.17763.8880
Windows 11 version 26H1 10.0.28000.0 <10.0.28000.2269
Windows 10 Version 1607 10.0.14393.0 <10.0.14393.9234
Windows Server 2012 R2 6.3.9600.0 <6.3.9600.23228
Windows Server 2025 10.0.26100.0 <10.0.26100.32995
Windows Server 2012 (Server Core installation) 6.2.9200.0 <6.2.9200.26132
Windows Server 2012 6.2.9200.0 <6.2.9200.26132
Windows Server 2012 R2 (Server Core installation) 6.3.9600.0 <6.3.9600.23228
Windows Server 2019 (Server Core installation) 10.0.17763.0 <10.0.17763.8880

Affected Packages

microsoft windows_10_version_1607_10_0_14393_9234 fix: Windows 10 Version 1607 for 32-bit Systems 10.0.14393.9234, Windows 10 Version 1607 for x64-based Systems 10.0.14393.9234
microsoft windows_10_version_1809_10_0_17763_8880 fix: Windows 10 Version 1809 for 32-bit Systems 10.0.17763.8880, Windows 10 Version 1809 for x64-based Systems 10.0.17763.8880
microsoft windows_10_version_21h2_10_0_19044_7417 fix: Windows 10 Version 21H2 for 32-bit Systems 10.0.19044.7417, Windows 10 Version 21H2 for ARM64-based Systems 10.0.19044.7417, Windows 10 Version 21H2 for x64-based Systems 10.0.19044.7417
microsoft windows_10_version_22h2_10_0_19045_7417 fix: Windows 10 Version 22H2 for 32-bit Systems 10.0.19045.7417, Windows 10 Version 22H2 for ARM64-based Systems 10.0.19045.7417, Windows 10 Version 22H2 for x64-based Systems 10.0.19045.7417
microsoft windows_11_version_23h2_10_0_22631_7219 fix: Windows 11 Version 23H2 for ARM64-based Systems 10.0.22631.7219, Windows 11 Version 23H2 for x64-based Systems 10.0.22631.7219
microsoft windows_11_version_24h2_10_0_26100_8655 fix: Windows 11 Version 24H2 for ARM64-based Systems 10.0.26100.8655, Windows 11 Version 24H2 for x64-based Systems 10.0.26100.8655
microsoft windows_11_version_25h2_10_0_26200_8655 fix: Windows 11 Version 25H2 for ARM64-based Systems 10.0.26200.8655, Windows 11 Version 25H2 for x64-based Systems 10.0.26200.8655
microsoft windows_11_version_26h1_10_0_28000_2269 fix: Windows 11 Version 26H1 for ARM64-based Systems 10.0.28000.2269, Windows 11 version 26H1 for x64-based Systems 10.0.28000.2269
microsoft windows_server_2012_6_2_9200_26132 fix: Windows Server 2012 6.2.9200.26132, Windows Server 2012 (Server Core installation) 6.2.9200.26132
microsoft windows_server_2012_r2_6_3_9600_23228 fix: Windows Server 2012 R2 6.3.9600.23228, Windows Server 2012 R2 (Server Core installation) 6.3.9600.23228
microsoft windows_server_2016_10_0_14393_9234 fix: Windows Server 2016 10.0.14393.9234, Windows Server 2016 (Server Core installation) 10.0.14393.9234
microsoft windows_server_2019_10_0_17763_8880 fix: Windows Server 2019 10.0.17763.8880, Windows Server 2019 (Server Core installation) 10.0.17763.8880
microsoft windows_server_2022_10_0_20348_5256 fix: Windows Server 2022 10.0.20348.5256, Windows Server 2022 (Server Core installation) 10.0.20348.5256
microsoft windows_server_2025_10_0_26100_32995 fix: Windows Server 2025 10.0.26100.32995, Windows Server 2025 (Server Core installation) 10.0.26100.32995
euvd windows_10_version_1607 fix: 10.0.14393.9234
euvd windows_10_version_1809 fix: 10.0.17763.8880
euvd windows_10_version_21h2 fix: 10.0.19044.7417
euvd windows_10_version_22h2 fix: 10.0.19045.7417
euvd windows_11_version_23h2 fix: 10.0.22631.7219
euvd windows_11_version_24h2 fix: 10.0.26100.8655
euvd windows_11_version_25h2 fix: 10.0.26200.8655
euvd windows_11_version_26h1 fix: 10.0.28000.2269
euvd windows_server_2012 fix: 6.2.9200.26132
euvd windows_server_2012_r2 fix: 6.3.9600.23228
euvd windows_server_2012_r2_server_core_installation fix: 6.3.9600.23228
euvd windows_server_2012_server_core_installation fix: 6.2.9200.26132
euvd windows_server_2016 fix: 10.0.14393.9234
euvd windows_server_2016_server_core_installation fix: 10.0.14393.9234
euvd windows_server_2019 fix: 10.0.17763.8880
euvd windows_server_2019_server_core_installation fix: 10.0.17763.8880
euvd windows_server_2022 fix: 10.0.20348.5256
euvd windows_server_2025 fix: 10.0.26100.32995
euvd windows_server_2025_server_core_installation fix: 10.0.26100.32995

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 33 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

Windows Kerberos is Microsoft's implementation of the Kerberos v5 authentication protocol, central to Active Directory domain authentication. CWE-476 (Null Pointer Dereference) identifies the root cause: a missing null check before a pointer dereference in the Kerberos processing code. When a specially crafted Kerberos message reaches the affected code path, the process attempts to dereference a null pointer, triggering an access violation that crashes the service. Given the network attack vector (AV:N) and low complexity (AC:L), the triggering condition is reachable through standard Kerberos protocol interactions, likely in authentication request parsing or ticket handling logic. Affected systems are primarily Windows hosts participating in Active Directory environments, including Domain Controllers and member servers. No CPE strings were provided in the source data; exact affected build numbers must be confirmed via the MSRC advisory.

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Severity by source

Vendor (microsoft) PRIMARY 6.5 MEDIUM
AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CIRCL (temporal) 5.7 MEDIUM

Primary rating from Vendor (microsoft).

CVSS VectorVendor: microsoft

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

2
Patch available
Jun 09, 2026 - 19:03 EUVD
CVE Published
Jun 09, 2026 - 17:17 nvd
MEDIUM 6.5

DescriptionCVE.org

Null pointer dereference in Windows Kerberos allows an authorized attacker to deny service over a network.

Threat Intelligence Overview

EPSS Score
0.2%
Top 61% exploitable
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
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 MEDIUM
CISA KEV No
Public POC No
EPSS 0.2%
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
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

32
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +32
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A null pointer dereference occurs when a program attempts to access memory through a pointer that has been set to NULL (address 0x0).

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