CVE-2026-40377: Microsoft Cryptographic Services Elevation of Privilege Vulnerability

Published May 12, 2026
·
Updated

Heap-based buffer overflow in Windows Cryptographic Services allows an authorized attacker to elevate privileges locally.

Other sources

Microsoft Cryptographic Services Elevation of Privilege Vulnerability

— Microsoft

Affected Software

56 affected componentsFixes available
Microsoft Windows 10 1607<10.0.14393.9140
Microsoft Windows 10 1607<10.0.14393.9140
Microsoft Windows 10 1809<10.0.17763.8755
Microsoft Windows 10 1809<10.0.17763.8755
Microsoft Windows 10 21h2<10.0.19044.7291
Microsoft Windows 10 21h2<10.0.19044.7291
Microsoft Windows 10 21h2<10.0.19044.7291
Microsoft Windows 10 22h2<10.0.19045.7291
Microsoft Windows 10 22h2<10.0.19045.7291
Microsoft Windows 10 22h2<10.0.19045.7291
Microsoft Windows 11 23h2<10.0.22631.7079
Microsoft Windows 11 23h2<10.0.22631.7079
Microsoft Windows 11 24h2<10.0.26100.8390
Microsoft Windows 11 24h2<10.0.26100.8390
Microsoft Windows 11 25h2<10.0.26200.8390
Microsoft Windows 11 25h2<10.0.26200.8390
Microsoft Windows 11 26h1<10.0.28000.2113
Microsoft Windows 11 26h1<10.0.28000.2113
Microsoft Windows Server 2012
Microsoft Windows Server 2012=r2
Microsoft Windows Server 2016<10.0.14393.9140
Microsoft Windows Server 2019<10.0.17763.8755
Microsoft Windows Server 2022<10.0.20348.5074
Microsoft Windows Server 2022 23h2<10.0.25398.2330
Microsoft Windows Server 2025<10.0.26100.32772
Microsoft Windows Server 2012 R2<6.3.9600.23181
6.3.9600.23181
Microsoft Windows Server 2012<6.2.9200.26079
6.2.9200.26079
Microsoft Windows Server 2012 R2<6.3.9600.23181
6.3.9600.23181
Microsoft Windows Server 2012<6.2.9200.26079
6.2.9200.26079
Microsoft Windows Server 2016<10.0.14393.9140
10.0.14393.9140
Microsoft Windows 11=26H1, >=10.0.28000<10.0.28000.2113
10.0.28000.2113
Microsoft Windows Server 2016<10.0.14393.9140
10.0.14393.9140
Microsoft Windows 10=1607, >=10.0.14393<10.0.14393.9140
10.0.14393.9140
Microsoft Windows 10=1607, >=10.0.14393<10.0.14393.9140
10.0.14393.9140
Microsoft Windows 11=26H1, >=10.0.28000<10.0.28000.2113
10.0.28000.2113
Microsoft Windows 11=24H2, >=10.0.26100<10.0.26100.8457, >=10.0.26100<10.0.26100.8390
10.0.26100.845710.0.26100.8390
Microsoft Windows Server 2025<10.0.26100.32860, <10.0.26100.32772
10.0.26100.3286010.0.26100.32772
Microsoft Windows Server 2022, 23H2 Edition<10.0.25398.2330
10.0.25398.2330
Microsoft Windows 11=24H2, >=10.0.26100<10.0.26100.8457, >=10.0.26100<10.0.26100.8390
10.0.26100.845710.0.26100.8390
Microsoft Windows Server 2025<10.0.26100.32860, <10.0.26100.32772
10.0.26100.3286010.0.26100.32772
Microsoft Windows 11=25H2, >=10.0.26200<10.0.26200.8457, >=10.0.26200<10.0.26200.8390
10.0.26200.845710.0.26200.8390
Microsoft Windows 11=23H2, >=10.0.22631<10.0.22631.7219
10.0.22631.7219
Microsoft Windows 11=25H2, >=10.0.26200<10.0.26200.8457, >=10.0.26200<10.0.26200.8390
10.0.26200.845710.0.26200.8390
Microsoft Windows 10=22H2, >=10.0.19045<10.0.19045.7417
10.0.19045.7417
Microsoft Windows 11=23H2, >=10.0.22631<10.0.22631.7079
10.0.22631.7079
Microsoft Windows 10=21H2, >=10.0.19044<10.0.19044.7291
10.0.19044.7291
Microsoft Windows 10=22H2, >=10.0.19045<10.0.19045.7417
10.0.19045.7417
Microsoft Windows Server 2022<10.0.20348.5139, <10.0.20348.5074
10.0.20348.513910.0.20348.5074
Microsoft Windows 10=22H2, >=10.0.19045<10.0.19045.7417
10.0.19045.7417
Microsoft Windows 10=21H2, >=10.0.19044<10.0.19044.7291
10.0.19044.7291
Microsoft Windows Server 2019<10.0.17763.8755
10.0.17763.8755
Microsoft Windows Server 2019<10.0.17763.8755
10.0.17763.8755
Microsoft Windows 10=1809, >=10.0.17763<10.0.17763.8755
10.0.17763.8755
Microsoft Windows 10=21H2, >=10.0.19044<10.0.19044.7291
10.0.19044.7291
Microsoft Windows 10=1809, >=10.0.17763<10.0.17763.8755
10.0.17763.8755
Microsoft Windows Server 2022<10.0.20348.5139, <10.0.20348.5074
10.0.20348.513910.0.20348.5074

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 6.3.9600.23181Patch KB5087471
  2. Upgrade

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

    Fixed in 10.0.14393.9140Patch KB5087537
  3. Upgrade

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

    Fixed in 10.0.26100.32860Fixed in 10.0.26100.32772Patch KB5087423
  4. Upgrade

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

    Fixed in 10.0.28000.2113Patch KB5089548
  5. Upgrade

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

    Fixed in 10.0.26100.8457Fixed in 10.0.26100.8390Patch KB5089466
  6. Upgrade

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

    Fixed in 10.0.22631.7219Patch KB5093998
  7. Upgrade

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

    Fixed in 10.0.22631.7079Patch KB5087420
  8. Upgrade

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

    Fixed in 10.0.25398.2330Patch KB5087541
  9. Upgrade

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

    Fixed in 10.0.26200.8457Fixed in 10.0.26200.8390Patch KB5089466
  10. Upgrade

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

    Fixed in 6.2.9200.26079Patch KB5087470
  11. Upgrade

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

    Fixed in 10.0.19045.7417Patch KB5094127
  12. Upgrade

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

    Fixed in 10.0.19044.7291Patch KB5087544
  13. Upgrade

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

    Fixed in 10.0.20348.5139Fixed in 10.0.20348.5074Patch KB5087424
  14. Upgrade

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

    Fixed in 10.0.17763.8755Patch KB5087538

Event History

May 12, 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
CVE Published
via MITRE·04:58 PM
Data Sourced
via MITRE·04:58 PM
DescriptionSeverity
Data Sourced
via NVD·06:17 PM
DescriptionSeverityWeaknessAffected Software

Frequently Asked Questions

1

What is the severity of CVE-2026-40377?

CVE-2026-40377 has been rated as a critical vulnerability due to its potential to allow unauthorized privilege escalation.

2

How do I fix CVE-2026-40377?

To mitigate CVE-2026-40377, apply the latest security patches provided by Microsoft for affected Windows products.

3

What systems are affected by CVE-2026-40377?

CVE-2026-40377 affects various Windows operating systems, including Windows Server 2025, Windows Server 2016, Windows 10, Windows Server 2012 R2, and others.

4

Can CVE-2026-40377 be exploited remotely?

CVE-2026-40377 requires local access, meaning an attacker must already have local access to the system to exploit it.

5

What should I do if I believe my system is affected by CVE-2026-40377?

If your system is affected by CVE-2026-40377, immediately apply the recommended security updates and assess your system's security posture.

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