CVE-2026-62889: Windows Secure Socket Tunneling Protocol (SSTP) Remote Code Execution Vulnerability

Published Aug 11, 2026
·
Updated

Double free in Windows Secure Socket Tunneling Protocol (SSTP) allows an unauthorized attacker to execute code over a network.

Other sources

Windows Secure Socket Tunneling Protocol (SSTP) Remote Code Execution Vulnerability

— Microsoft

Affected Software

30 affected componentsFixes available
Microsoft Windows 10=1809
10.0.17763.9115
Microsoft Windows Server 2022<10.0.20348.5499, <10.0.20348.5440
10.0.20348.549910.0.20348.5440
Microsoft Windows 10=21H2
10.0.19044.7663
Microsoft Windows Server 2022<10.0.20348.5499, <10.0.20348.5440
10.0.20348.549910.0.20348.5440
Microsoft Windows Server 2019<10.0.17763.9115
10.0.17763.9115
Microsoft Windows Server 2019<10.0.17763.9115
10.0.17763.9115
Microsoft Windows 10=1809
10.0.17763.9115
Microsoft Windows Server 2012 R2<6.3.9600.23337
6.3.9600.23337
Microsoft Windows Server 2012 R2<6.3.9600.23337
6.3.9600.23337
Microsoft Windows 10=21H2
10.0.19044.7663
Microsoft Windows Server 2012<6.2.9200.26279
6.2.9200.26279
Microsoft Windows Server 2012<6.2.9200.26279
6.2.9200.26279
Microsoft Windows 11=26H1
10.0.28000.2704
Microsoft Windows Server 2016<10.0.14393.9418
10.0.14393.9418
Microsoft Windows 10=1607
10.0.14393.9418
Microsoft Windows Server 2016<10.0.14393.9418
10.0.14393.9418
Microsoft Windows 10=1607
10.0.14393.9418
Microsoft Windows Server 2025<10.0.26100.33296, <10.0.26100.33222
10.0.26100.3329610.0.26100.33222
Microsoft Windows 11=26H1
10.0.28000.2704
Microsoft Windows 11=24H2
10.0.26100.916810.0.26100.9106
Microsoft Windows 11=23H2
10.0.22631.7517
Microsoft Windows Server 2025<10.0.26100.33296, <10.0.26100.33222
10.0.26100.3329610.0.26100.33222
Microsoft Windows 10=22H2
10.0.19045.7663
Microsoft Windows 11=25H2
10.0.26200.916810.0.26100.9106
Microsoft Windows 11=25H2
10.0.26200.916810.0.26100.9106
Microsoft Windows 10=22H2
10.0.19045.7663
Microsoft Windows 10=22H2
10.0.19045.7663
Microsoft Windows 11=24H2
10.0.26100.916810.0.26000.9106
Microsoft Windows 11=23H2
10.0.22631.7517
Microsoft Windows 10=21H2
10.0.19044.7663

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.17763.9115Patch KB5120238
  2. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.20348.5499Fixed in 10.0.20348.5440Patch KB5120229
  3. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.19044.7663Patch KB5120249
  4. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 6.3.9600.23337Patch KB5120386
  5. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 6.2.9200.26279Patch KB5120385
  6. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.28000.2704Patch KB5121000
  7. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.14393.9418Patch KB5120418
  8. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.26100.33296Fixed in 10.0.26100.33222Patch KB5120228
  9. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.26100.9168Fixed in 10.0.26100.9106Patch KB5120994
  10. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.22631.7517Patch KB5120240
  11. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.19045.7663Patch KB5120249
  12. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.26200.9168Fixed in 10.0.26100.9106Patch KB5120994
  13. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.26100.9168Fixed in 10.0.26000.9106Patch KB5120994

Event History

Aug 11, 2026
CVE Published
via Microsoft·02:00 PM
Data Sourced
via Microsoft·02:00 PM
DescriptionSeverityWeakness
Data Sourced
via Microsoft·02:00 PM
Affected Software
Updated
via Microsoft·02:00 PM
Description
CVE Published
via MITRE·05:04 PM
Data Sourced
via MITRE·05:04 PM
DescriptionSeverity
Data Sourced
via NVD·05:18 PM
DescriptionSeverityWeakness
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Frequently Asked Questions

1

What is the severity of CVE-2026-62889?

CVE-2026-62889 has a severity rating of 8.1, categorized as high.

2

How does CVE-2026-62889 affect Microsoft Windows?

CVE-2026-62889 allows an unauthorized attacker to execute code remotely by exploiting a double free vulnerability in the Windows Secure Socket Tunneling Protocol (SSTP).

3

How do I fix CVE-2026-62889?

To mitigate CVE-2026-62889, apply the latest security updates provided by Microsoft for affected Windows versions.

4

Which versions of Windows are affected by CVE-2026-62889?

CVE-2026-62889 affects Microsoft Windows 10, Windows 11, and various versions of Windows Server including 2012, 2016, 2019, 2022, and 2025.

5

What is the impact of a successful exploit of CVE-2026-62889?

Successful exploitation of CVE-2026-62889 could allow an attacker to execute arbitrary code on the targeted system.

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