Windows Kerberos
CVE-2021-31962 — Kerberos AppContainer Security Feature Bypass Vulnerability
Executive Summary
None
Overview
9.4
CVSS CRITICAL
Important
MS Severity
Not Exploited
MS Exploit Status
Less Likely
MS Exploit Likelihood
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C
ATTACK VECTOR
Network
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
None
USER INTERACTION
None
SCOPE
Unchanged
CONFIDENTIALITY
High
INTEGRITY
High
AVAILABILITY
Low
EXPLOIT CODE MATURITY
Unproven
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 8.2
EPSS Score
0.03808
probability of exploitation in the next 30 days
0.88649 percentile - updated 2026-06-21
View on FIRST.org
Affected Products
25 affected products
| Product | KB Article | Severity | Impact | Restart Required |
|---|---|---|---|---|
| Windows 10 for 32-bit Systems | 5003687 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows 10 for x64-based Systems | 5003687 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows 10 Version 1607 for 32-bit Systems | 5003638 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows 10 Version 1607 for x64-based Systems | 5003638 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows 10 Version 1809 for 32-bit Systems | 5003646 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows 10 Version 1809 for ARM64-based Systems | 5003646 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows 10 Version 1809 for x64-based Systems | 5003646 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows 10 Version 1909 for 32-bit Systems | 5003635 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows 10 Version 1909 for ARM64-based Systems | 5003635 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows 10 Version 1909 for x64-based Systems | 5003635 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows 10 Version 2004 for 32-bit Systems | 5003637 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows 10 Version 2004 for ARM64-based Systems | 5003637 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows 10 Version 2004 for x64-based Systems | 5003637 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows 10 Version 20H2 for 32-bit Systems | 5003637 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows 10 Version 20H2 for ARM64-based Systems | 5003637 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows 10 Version 21H1 for 32-bit Systems | 5003637 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows 10 Version 21H1 for ARM64-based Systems | 5003637 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows 10 Version 21H1 for x64-based Systems | 5003637 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows 7 for 32-bit Systems Service Pack 1 5003667 (Monthly Rollup) 5003694 (Security Only) Important Security Feature Bypass 5003233 Base: 9.4 Temporal: 8.2 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C 6.1.7601.25632 Yes None Windows 7 for x64-based Systems Service Pack 1 5003667 (Monthly Rollup) 5003694 (Security Only) Important Security Feature Bypass 5003233 Base: 9.4 Temporal: 8.2 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C 6.1.7601.25632 Yes None Windows 8.1 for 32-bit systems 5003671 (Monthly Rollup) 5003681 (Security Only) Important Security Feature Bypass 5003209 Base: 9.4 Temporal: 8.2 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C 6.3.9600.20045 6.3.9600.20044 Yes None Windows 8.1 for x64-based systems 5003671 (Monthly Rollup) 5003681 (Security Only) Important Security Feature Bypass 5003209 Base: 9.4 Temporal: 8.2 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C 6.3.9600.20045 6.3.9600.20044 Yes None Windows RT 8.1 | 5003671 (Monthly Rollup) |
Important | Security Feature Bypass | Yes |
| Windows Server 2008 for 32-bit Systems Service Pack 2 5003661 (Monthly Rollup) 5003695 (Security Only) Important Security Feature Bypass 5003210 Base: 9.4 Temporal: 8.2 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C 6.0.6003.21137 Yes None Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation) 5003661 (Monthly Rollup) 5003695 (Security Only) Important Security Feature Bypass 5003210 Base: 9.4 Temporal: 8.2 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C 6.0.6003.21137 Yes None Windows Server 2008 for x64-based Systems Service Pack 2 5003661 (Monthly Rollup) 5003695 (Security Only) Important Security Feature Bypass 5003210 Base: 9.4 Temporal: 8.2 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C 6.0.6003.21137 Yes None Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation) 5003661 (Monthly Rollup) 5003695 (Security Only) Important Security Feature Bypass 5003210 Base: 9.4 Temporal: 8.2 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C 6.0.6003.21137 Yes None Windows Server 2008 R2 for x64-based Systems Service Pack 1 5003667 (Monthly Rollup) 5003694 (Security Only) Important Security Feature Bypass 5003233 Base: 9.4 Temporal: 8.2 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C 6.1.7601.25632 Yes None Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) 5003667 (Monthly Rollup) 5003694 (Security Only) Important Security Feature Bypass 5003233 Base: 9.4 Temporal: 8.2 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C 6.1.7601.25632 Yes None Windows Server 2012 5003697 (Monthly Rollup) 5003696 (Security Only) Important Security Feature Bypass 5003208 Base: 9.4 Temporal: 8.2 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C 6.2.9200.23372 Yes None Windows Server 2012 (Server Core installation) 5003697 (Monthly Rollup) 5003696 (Security Only) Important Security Feature Bypass 5003208 Base: 9.4 Temporal: 8.2 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C 6.2.9200.23372 Yes None Windows Server 2012 R2 5003671 (Monthly Rollup) 5003681 (Security Only) Important Security Feature Bypass 5003209 Base: 9.4 Temporal: 8.2 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C 6.3.9600.20045 6.3.9600.20044 Yes None Windows Server 2012 R2 (Server Core installation) 5003671 (Monthly Rollup) 5003681 (Security Only) Important Security Feature Bypass 5003209 Base: 9.4 Temporal: 8.2 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C 6.3.9600.20045 6.3.9600.20044 Yes None Windows Server 2016 | 5003638 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows Server 2016 (Server Core installation) | 5003638 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows Server 2019 | 5003646 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows Server 2019 (Server Core installation) | 5003646 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows Server, version 2004 (Server Core installation) | 5003637 (Security Update) |
Important | Security Feature Bypass | Yes |
| Windows Server, version 20H2 (Server Core Installation) | 5003637 (Security Update) |
Important | Security Feature Bypass | Yes |
Patches
6 patches
| Article | Type | Restart |
|---|---|---|
5003687 |
Security Update | Yes |
5003638 |
Security Update | Yes |
5003646 |
Security Update | Yes |
5003635 |
Security Update | Yes |
5003637 |
Security Update | Yes |
5003671 |
Monthly Rollup | Yes |
Known Exploits
No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.
Acknowledgments
James Forshaw of Google Project Zero
References
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