CyberSecBulletin
CVE-2026-87705NVD status: Analyzed

Windows 10 Version 1607: Improper Verification of Source of a Communication Channel

Published Updated By the CyberSecBulletin desk

CVE-2026-87705 is a high-severity improper verification of source of a communication channel vulnerability in Windows 10 Version 1607 from Microsoft, with a CVSS 3.1 base score of 7.4 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists version 10.0.14393.9612 as the first without the flaw, so updating Windows 10 Version 1607 to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.43% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Windows 10 Version 1607 to 10.0.14393.9612 or a later version.
  2. Update Windows 10 Version 1809 to 10.0.17763.9376 or a later version.
  3. Update Windows 10 Version 21H2 to 10.0.19044.7807 or a later version.
  4. Read the advisory on msrc.microsoft.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
MicrosoftWindows 10 Version 160710.0.14393.0 up to, but not including, 10.0.14393.961210.0.14393.9612
MicrosoftWindows 10 Version 180910.0.17763.0 up to, but not including, 10.0.17763.937610.0.17763.9376
MicrosoftWindows 10 Version 21H210.0.19044.0 up to, but not including, 10.0.19044.780710.0.19044.7807
MicrosoftWindows 10 Version 22H210.0.19045.0 up to, but not including, 10.0.19045.780710.0.19045.7807
MicrosoftWindows 11 version 23H210.0.22631.0 up to, but not including, 10.0.22631.765210.0.22631.7652
MicrosoftWindows 11 Version 24H210.0.26100.0 up to, but not including, 10.0.26100.971110.0.26100.9711
MicrosoftWindows 11 Version 25H210.0.26200.0 up to, but not including, 10.0.26200.971110.0.26200.9711
MicrosoftWindows 11 version 26H110.0.28000.0 up to, but not including, 10.0.28000.323110.0.28000.3231
MicrosoftWindows 11 Version 26H210.0.26300.0 up to, but not including, 10.0.26300.971110.0.26300.9711
MicrosoftWindows Server 20126.2.9200.0 up to, but not including, 6.2.9200.264346.2.9200.26434
MicrosoftWindows Server 2012 (Server Core installation)6.2.9200.0 up to, but not including, 6.2.9200.264346.2.9200.26434
MicrosoftWindows Server 2012 R26.3.9600.0 up to, but not including, 6.3.9600.234706.3.9600.23470
MicrosoftWindows Server 2012 R2 (Server Core installation)6.3.9600.0 up to, but not including, 6.3.9600.234706.3.9600.23470
MicrosoftWindows Server 201610.0.14393.0 up to, but not including, 10.0.14393.961210.0.14393.9612
MicrosoftWindows Server 2016 (Server Core installation)10.0.14393.0 up to, but not including, 10.0.14393.961210.0.14393.9612
MicrosoftWindows Server 201910.0.17763.0 up to, but not including, 10.0.17763.937610.0.17763.9376
MicrosoftWindows Server 2019 (Server Core installation)10.0.17763.0 up to, but not including, 10.0.17763.937610.0.17763.9376
MicrosoftWindows Server 202210.0.20348.0 up to, but not including, 10.0.20348.576110.0.20348.5761
MicrosoftWindows Server 202510.0.26100.0 up to, but not including, 10.0.26100.3365010.0.26100.33650
MicrosoftWindows Server 2025 (Server Core installation)10.0.26100.0 up to, but not including, 10.0.26100.3365010.0.26100.33650
MicrosoftWindows 10 1607before 10.0.14393.961210.0.14393.9612
MicrosoftWindows 10 1809before 10.0.17763.937610.0.17763.9376
MicrosoftWindows 10 21h2before 10.0.19044.780710.0.19044.7807
MicrosoftWindows 10 22h2before 10.0.19045.780710.0.19045.7807
MicrosoftWindows 11 23h2before 10.0.22631.765210.0.22631.7652

Version data comes from the organisation that assigned the CVE; 4 further products are omitted here. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
AdjacentThe attacker must be on the same local network segment.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
ChangedThe attack can reach beyond the vulnerable component into other systems.
Confidentiality
HighAll data handled by the component can be read.
Integrity
NoneNothing can be modified.
Availability
NoneAvailability is not affected.

Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N. Scored by CNA (microsoft.com).

Official description

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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: 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.

How developers prevent this class of flaw

  • Use a mechanism that can validate the identity of the source, such as a certificate, and validate the integrity of data to ensure that it cannot be modified in transit using an Adversary-in-the-Middle (AITM) attack. When designing functionality of actions in the URL scheme, consider whether the action should be accessible to all mobile applications, or if an allowlist of applications to interface with is appropriate.

More Improper Verification of Source of a Communication Channel vulnerabilities (CWE-940)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Improper Verification of Source of a Communication Channel vulnerabilities

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