Evidence used
- No CISA KEV confirmation is currently recorded.
- EPSS is 0.35% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-87705High confidence
Windows Hyper-V Security Feature Bypass Vulnerability
Microsoft · Windows 10 Version 1607
7.4HighCVSS 3.1
Within 7 days
Patch availableHigh technical severity; prioritise exposed affected systems while verifying vendor guidance.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:High, unchanged from published severity.unchanged
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict local access and enforce least privilege on affected hosts.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Microsoft Windows 10 Version 1607 and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
High technical severity; prioritise exposed affected systems while verifying vendor guidance.
Patch available01
What, why and how
Improper verification of source of a communication channel in Windows Hyper-V allows an unauthorized attacker to bypass a security feature over an adjacent network.
What
Improper verification of source of a communication channel in Windows Hyper-V allows an unauthorized attacker to bypass a security feature over an adjacent network.
Why
The product establishes a communication channel to handle an incoming request that has been initiated by an actor, but it does not properly verify that the request is coming from the expected origin.
How
An attacker operating through an adjacent network may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
Improper verification of source of a communication channel in Windows Hyper-V allows an unauthorized attacker to bypass a security feature over an adjacent network.
Why
The product establishes a communication channel to handle an incoming request that has been initiated by an actor, but it does not properly verify that the request is coming from the expected origin.
How
An attacker operating through an adjacent network may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- an adjacent network → Improper Verification of Source of a Communication Channel → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Adjacent
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Changed: exploitation can affect a different security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-940 ↗
CWE-940: Improper Verification of Source of a Communication Channel. The product establishes a communication channel to handle an incoming request that has been initiated by an actor, but it does not properly verify that the request is coming from the expected origin.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N/E:U/RL:O/RC:CCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVAdjacentAttack vector: The attacker must be on an adjacent or logically close network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SChangedScope: The attack can affect a component governed by a different security authority.CHighConfidentiality impact: A successful attack can cause a major loss.INoneIntegrity impact: No direct loss is represented by this metric.ANoneAvailability impact: No direct loss is represented by this metric.- Post-exploitation / living off the land
- No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Patch available
- Affected
- Windows 10 Version 1607: 10.0.14393.0 < 10.0.14393.9612
- Windows 10 Version 1809: 10.0.17763.0 < 10.0.17763.9376
- Windows 10 Version 21H2: 10.0.19044.0 < 10.0.19044.7807
- Windows 10 Version 22H2: 10.0.19045.0 < 10.0.19044.7807
- Windows 11 version 23H2: 10.0.22631.0 < 10.0.22631.7652
- Windows 11 Version 23H2: 10.0.22631.0 < 10.0.22631.7652
- Windows 11 Version 24H2: 10.0.26100.0 < 10.0.26100.9711
- Windows 11 Version 25H2: 10.0.26200.0 < 10.0.26200.9711
- Windows 11 version 26H1: 10.0.28000.0 < 10.0.28000.3231
- Windows 11 Version 26H2: 10.0.26300.0 < 10.0.26300.9711
- Windows Server 2012: 6.2.9200.0 < 6.2.9200.26434
- 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 Server 2012 R2 (Server Core installation): 6.3.9600.0 < 6.3.9600.23470
- Windows Server 2016: 10.0.14393.0 < 10.0.14393.9612
- Windows Server 2016 (Server Core installation): 10.0.14393.0 < 10.0.14393.9612
- Windows Server 2019: 10.0.17763.0 < 10.0.17763.9376
- 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 Server 2025: 10.0.26100.0 < 10.0.26100.33650
- Windows Server 2025 (Server Core installation): 10.0.26100.0 < 10.0.26100.33650
- Action
- Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
- Workaround
- No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
Official vendor articles10 stored documents
Linked articles are downloaded and versioned as source evidence. A CVE mention or approved update relationship does not, by itself, verify a fix for every product branch.
- October 13, 2026—KB5126646 (OS Build 26100.33650) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 14 Oct 2026October 13, 2026—KB5126646 (OS Build 26100.33650) Applies To Windows Server 2025, all editions This cumulative update for Windows Server 2025 (KB5126646), includes the latest security fixes and improvements, along with non-security updates from last month’s optional preview release. Visit the Windows release health da
- October 13, 2026—KB5126651 (OS Build 17763.9376) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 14 Oct 2026October 13, 2026—KB5126651 (OS Build 17763.9376) Applies To Windows Server 2019 Win 10 Ent LTSC 2019 Summary This article lists the security issues and quality improvements included in this cumulative security update. Windows Server 2019 Windows 10, version 1809 Applies to: Windows Server 2019 This security update i
- October 13, 2026—KB5126653 (OS Build 22621.7652) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 14 Oct 2026October 13, 2026—KB5126653 (OS Build 22621.7652) Applies To Windows 11 version 23H2, all editions This cumulative update for Windows 11, version 23H2 (KB5126653), includes the latest security fixes and improvements, along with non-security updates from last month’s optional preview release. Visit the Windows release h
- October 13, 2026—KB5126655 (OS Build 20348.5761) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 14 Oct 2026October 13, 2026—KB5126655 (OS Build 20348.5761) Applies To Windows Server 2022 This cumulative update for Windows Server 2022 (KB5126655), includes the latest security fixes and improvements, along with non-security updates from last month’s optional preview release. Visit the Windows release health dashboard for the
- October 13, 2026—KB5126657 (OS Builds 19045.7807 and 19044.7807) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 14 Oct 2026October 13, 2026—KB5126657 (OS Builds 19045.7807 and 19044.7807) Applies To Windows 10 ESU Windows 10 Enterprise LTSC 2021 Windows 10 IoT Enterprise LTSC 2021 Important Free support for Windows 10 Enterprise LTSC 2021 ends on January 12, 2027. To learn about continuing support, see Plan for Windows 10 Enterprise LTSC
- October 13, 2026—KB5126835 (Monthly Rollup) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 14 Oct 2026October 13, 2026—KB5126835 (Monthly Rollup) Applies To Windows Server 2012 ESU Important The installation of this Extended Security Update (ESU) might fail when you try to install it on an Azure Arc-enabled device that is running Windows Server 2012. For a successful installation, please make sure all Subset of endpoi
- October 13, 2026—KB5126836 (Monthly Rollup) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 14 Oct 2026October 13, 2026—KB5126836 (Monthly Rollup) Applies To Windows Server 2012 R2 ESU Important The installation of this Extended Security Update (ESU) might fail when you try to install it on an Azure Arc-enabled device that is running Windows Server 2012 R2. For a successful installation, please make sure all Subset of
- October 13, 2026—KB5126868 (OS Build 14393.9612) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 14 Oct 2026October 13, 2026—KB5126868 (OS Build 14393.9612) Applies To Windows Server 2016, all editions Win 10 Ent LTSB 2016 Win 10 IoT Ent LTSB 2016 Important Free support for Windows 10 Enterprise LTSB 2016 and Windows 10 IoT Enterprise 2016 LTSB ends on October 13, 2026. Free support for Windows Server 2016 ends soon. To lea
- October 13, 2026—KB5127646 (OS Build 28000.3231) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 14 Oct 2026October 13, 2026—KB5127646 (OS Build 28000.3231) Applies To Windows 11 version 26H1, all editions This cumulative update for Windows 11, version 26H1 (KB5127646) includes the latest security fixes and improvements, along with non-security updates from last month's optional preview release. Visit the Windows release he
- October 13, 2026—KB5127648 (OS Builds 26300.9711, 26200.9711 and 26100.9711) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 14 Oct 2026October 13, 2026—KB5127648 (OS Builds 26300.9711, 26200.9711 and 26100.9711) Applies To Windows 11 version 26H2, all editions Windows 11 version 25H2, all editions Windows 11 version 24H2, all editions Want a quick overview?: Watch the Windows 11 release note video for this update. Announcements and messages This sec
04
Evidence and provenance
Published 13 Oct 2026 · Last source change 14 Oct 2026, 17:57 UTC · CWE-940 · Improper Verification of Source of a Communication Channel
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-10-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-100072
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceOther authority
NVD statusNVD awaiting enrichment
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- Vendor guidanceAuthoritative vendor guidance changed: removed remediation: acn.gov.it/aggiornamenti-mensili-microsoft-25.CNA ↗
- Before
- remediation: acn.gov.it/aggiornamenti-mensili-microsoft-25
- After
- no authoritative guidance recorded
- Remediation statusRemediation status changed from Mitigation available to Awaiting fix.CNA ↗
- Before
- Mitigation available
- After
- Awaiting fix
- Vendor guidanceAuthoritative vendor guidance changed: removed remediation: acn.gov.it/aggiornamenti-mensili-microsoft-25.CNA ↗
- Before
- remediation: acn.gov.it/aggiornamenti-mensili-microsoft-25
- After
- no authoritative guidance recorded
- Remediation statusRemediation status changed from Mitigation available to Awaiting fix.CNA ↗
- Before
- Mitigation available
- After
- Awaiting fix
- Remediation statusRemediation status changed from Awaiting fix to Mitigation available.CSIRT Italia ↗
- Before
- Awaiting fix
- After
- Mitigation available
- ENISA EUVD mappingEUVD-2026-100072 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2026-100072"}
- Catalogue recordCVE added to the BlackTree catalogue.CNA ↗
- CVSS scoreCVSS vector changed while the displayed base score remained 7.4.CNA ↗
- Before
- 7.4 (CVSS 3.1 · CNA · CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N)
- After
- 7.4 (CVSS 3.1 · CNA · CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N/E:U/RL:O/RC:C)
CVE published
Remediation guidance recorded
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.