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Windows Kerberos CVE-2026-70241

| EUVDEUVD-2026-99417 HIGH
Use After Free (CWE-416)
2026-10-13 secure@microsoft.com GHSA-9qqw-2w7p-94c4
7.0
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
    Authenticate as low-privileged local user
  2. Delivery
    Trigger use-after-free in Windows Kerberos
  3. Exploit
    Win freed-memory reuse race (AC:H)
  4. Execution
    Corrupt memory and hijack execution
  5. Impact
    Elevate to SYSTEM privileges

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

Exploitation requires the attacker to already possess authenticated, low-privileged local access to the target host (CVSS PR:L, AV:L) - this is a post-compromise privilege-escalation primitive, not a remotely reachable flaw. The specific prerequisite is the ability to invoke the vulnerable Windows Kerberos code paths and trigger the use-after-free condition; no special non-default configuration is named in the description, so default Windows installations running the affected builds are susceptible. The primary limiting factor is the high attack complexity (AC:H): the use-after-free must be won through a timing/race window, making reliable exploitation difficult, and there is no user interaction required (UI:N) but also no remote or unauthenticated path.

Impact

This is a credible but second-tier priority. The CVSS 3.1 vector (AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H, score 7.0 HIGH) describes a local privilege-escalation flaw: the attacker must already have a foothold as an authenticated low-privileged user (PR:L), execute locally (AV:L), and overcome high attack complexity (AC:H) - consistent with winning a timing/race window typical of use-after-free (CWE-416) bugs. The SSVC decision framework corroborates a measured posture: Exploitation=none and Automatable=no, but Technical Impact=total (matching C:H/I:H/A:H, i.e. full compromise of the local system once exploited). There is no CISA KEV listing and no public exploit (no public exploit identified at time of analysis), so there is no evidence of active exploitation. No EPSS score was supplied in the input, so exploitation probability cannot be quantified here - this is a data gap, not a signal of low risk. The signals are internally consistent (local, hard-to-exploit, high impact, no known exploitation), so this is a patch-in-normal-cycle item rather than an emergency, but because it affects the Windows Kerberos component across virtually all supported Windows client and server builds, it is a valuable post-compromise escalation primitive and should be prioritized above typical HIGH issues on multi-user and server hosts.

Exploit ScenarioDerived

An attacker who has already gained low-privileged code execution on a Windows host (e.g., via phishing, a compromised service account, or a standard user login) triggers the use-after-free in the Kerberos component by racing a specifically timed sequence of operations. Successful exploitation corrupts kernel/service memory and lets the attacker elevate to SYSTEM-level privileges. No public proof-of-concept or exploit code has been identified at the time of analysis, and the high attack complexity (AC:H) means exploitation requires reliably winning a memory-reuse race.

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 – Oct 14, 2026

Local privilege escalation in the Windows Kerberos implementation allows an authenticated, low-privileged attacker who already has code execution on a target host to escalate to higher integrity and potentially SYSTEM-level rights through a use-after-free memory corruption. Exploitation is restricted to the local attack surface and carries high attack complexity (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H), meaning the attacker must win a timing/race window against the freed Kerberos memory object, but no user interaction is needed and no non-default configuration is named as a prerequisite. There is no public exploit identified at time of analysis and no confirmed active exploitation (CISA SSVC exploitation: none), so this is best treated as a post-compromise escalation primitive that is difficult but high-impact if successfully triggered.

RemediationAI

Apply the Microsoft security update referenced in the MSRC advisory (https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-70241); patch availability is confirmed by the vendor, and remediation is reached by updating each affected branch to at least its EUVD-listed fixed build - for example 10.0.22631.7652 for Windows 11 23H2, 10.0.26100.9711 and 10.0.26100.33650 for the Windows 11 24H2 and Server 2025 branches respectively, 10.0.26200.9711 for 25H2, 10.0.26300.9711 for 26H2, 10.0.28000.3231 for 26H1, 10.0.19044.7807 for Windows 10 21H2/22H2, 10.0.14393.9612 for Windows 10 1607 and Server 2016, 10.0.17763.9376 for Windows 10 1809 and Server 2019, 10.0.20348.5761 for Server 2022, 6.2.9200.26434 for Server 2012, and 6.3.9600.23470 for Server 2012 R2. Until patching completes, the only broadly effective compensating control is to reduce the population of accounts that can obtain the authenticated local access this primitive requires: strip local interactive/RDP logon rights and administrative group membership from non-essential users, and segment hosts so that a foothold under a low-privileged account is harder to obtain - the trade-off is tighter operational friction for legitimate local and remote administration. Enabling LSA protection (RunAsPPL) and Credential Guard does not close the use-after-free itself but raises the cost of post-exploitation activity in the LSA process; disabling or restricting Kerberos is not a viable workaround because it is the core authentication mechanism for Active Directory domains. Monitor for LSA/kerberos-related crashes and unexpected privileged token or impersonation activity, which both signals exploitation attempts (including the denial-of-service manifestation noted in the CVE tags) and provides detection coverage while remediation is staged.

Affected VersionsENISA

Windows 11 Version 25H2 10.0.26200.0 <10.0.26200.9711
Windows Server 2019 10.0.17763.0 <10.0.17763.9376
Windows 11 Version 26H2 10.0.26300.0 <10.0.26300.9711
Windows Server 2025 (Server Core installation) 10.0.26100.0 <10.0.26100.33650
Windows Server 2016 10.0.14393.0 <10.0.14393.9612
Windows Server 2012 6.2.9200.0 <6.2.9200.26434
Windows 10 Version 21H2 10.0.19044.0 <10.0.19044.7807
Windows Server 2012 (Server Core installation) 6.2.9200.0 <6.2.9200.26434
Windows Server 2012 R2 6.3.9600.0 <6.3.9600.23470
Windows 11 Version 24H2 10.0.26100.0 <10.0.26100.9711
Windows 10 Version 1607 10.0.14393.0 <10.0.14393.9612
Windows Server 2016 (Server Core installation) 10.0.14393.0 <10.0.14393.9612
Windows Server 2022 10.0.20348.0 <10.0.20348.5761
Windows 10 Version 1809 10.0.17763.0 <10.0.17763.9376
Windows Server 2025 10.0.26100.0 <10.0.26100.33650
Windows 11 version 26H1 10.0.28000.0 <10.0.28000.3231
Windows Server 2012 R2 (Server Core installation) 6.3.9600.0 <6.3.9600.23470
Windows 11 Version 23H2 10.0.22631.0 <10.0.22631.7652
Windows Server 2019 (Server Core installation) 10.0.17763.0 <10.0.17763.9376
Windows 10 Version 22H2 10.0.19045.0 <10.0.19044.7807

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 root cause is CWE-416, Use After Free, in Microsoft's Kerberos security support provider (SSP) code paths within the Windows Local Security Authority (LSA) subsystem. Kerberos is the default network authentication protocol in Active Directory domains, and its client-side and server-side ticket handling runs in privileged LSA context; a use-after-free occurs when a Kerberos-related memory object is freed but subsequently dereferenced, letting the attacker influence the contents of reclaimed memory. Because the flaw lives in LSA, successful exploitation yields code execution at the integrity level of the LSA process - the classic local privilege-escalation outcome - and the associated tags (Memory Corruption, Use After Free, Denial Of Service) reflect that an uncontrolled dereference can also crash the service, producing a denial-of-service side effect even when privilege escalation fails. The CVSS vector's AV:L/PR:L combination confirms the vulnerability is not remotely reachable and requires the attacker to already hold authenticated low-privileged access from which the vulnerable Kerberos routines can be invoked locally; AC:H reflects that the heap/race grooming needed to reliably weaponize the freed object is nontrivial and not automatable (CISA SSVC Automatable: no).

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (microsoft) PRIMARY 7.0 HIGH
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
vuln.today AI 7.0 HIGH

Local post-authentication escalation (AV:L, PR:L), AC:H because the use-after-free requires winning a memory-reuse race, yielding full SYSTEM compromise (C:H/I:H/A:H).

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

Lifecycle Timeline

2
Patch available
Oct 13, 2026 - 20:20 EUVD
CVE Published
Oct 13, 2026 - 19:19 cve.org
HIGH 7.0

DescriptionCVE.org

Use after free in Windows Kerberos allows an authorized attacker to elevate privileges locally.

Executive ViewAI

Why It Matters

Microsoft Windows Kerberos contains a high-severity local privilege escalation vulnerability (CVE-2026-70241) that could allow an attacker with existing low-privileged access to a host to gain SYSTEM-level control. This elevates the risk of any initial compromise, enabling attackers to move laterally and access sensitive data. Leadership should prioritize patching because it turns a limited foothold into a full system breach, increasing the potential for ransomware or data theft.

Business Impact: High
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.3%
Top 82% exploitable
Prevalence
Ubiquitous
Core Windows component present on nearly all Windows client and server installations
Vendor Status
Publicly Disclosed:No
Exploited:No
Latest Software Release:Exploitation More 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 0.3%
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
Defer
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

35
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +35
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.

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

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