CVE-2021-31962 [Critical] | Security Bypass in Windows 10

CVE-2021-31962 is rated Moderate Risk (63.6/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 3.81%). Review affected assets and schedule remediation.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	17.79%	3.81%	-13.98%
2	2025-12-28	14.96%	17.79%	+2.84%
3	2025-12-27	—	14.96%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

17.79%

3.81%

-13.98%

2025-12-28

14.96%

17.79%

+2.84%

2025-12-27

—

14.96%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
9.4	3.1	CRITICAL	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:L) Might cause slowdowns, glitches, or partial disruption—not a full brick.	3.9	5.5	[email protected]
9.8	3.1	CRITICAL	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	5.9	[email protected]
7.5	2.0	HIGH	`AV:N/AC:L/Au:N/C:P/I:P/A:P` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:N) No authentication is required. Confidentiality impact (C:P) Partial confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:P) Partial availability impact.	10.0	6.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

9.4

3.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:L): Might cause slowdowns, glitches, or partial disruption—not a full brick.

3.9

5.5

[email protected]

9.8

3.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.9

5.9

[email protected]

7.5

2.0

HIGH

AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:P): Partial confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:P): Partial availability impact.

10.0

6.4

[email protected]

Affected software / configurations for CVE-2021-31962

Vendor	Product	Version	Raw CPE
microsoft	windows_10	—	cpe:2.3:o:microsoft:windows_10:-:::::::*
microsoft	windows_10	20h2	cpe:2.3:o:microsoft:windows_10:20h2:::::::*
microsoft	windows_10	21h1	cpe:2.3:o:microsoft:windows_10:21h1:::::::*
microsoft	windows_10	1607	cpe:2.3:o:microsoft:windows_10:1607:::::::*
microsoft	windows_10	1809	cpe:2.3:o:microsoft:windows_10:1809:::::::*
microsoft	windows_10	1909	cpe:2.3:o:microsoft:windows_10:1909:::::::*
microsoft	windows_10	2004	cpe:2.3:o:microsoft:windows_10:2004:::::::*
microsoft	windows_7	—	cpe:2.3:o:microsoft:windows_7:-:sp1::::::
microsoft	windows_8.1	—	cpe:2.3:o:microsoft:windows_8.1:-:::::::*
microsoft	windows_rt_8.1	—	cpe:2.3:o:microsoft:windows_rt_8.1:-:::::::*
microsoft	windows_server_2008	r2	cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:::::x64:*
microsoft	windows_server_2008	sp2	cpe:2.3:o:microsoft:windows_server_2008:sp2:::::::*
microsoft	windows_server_2012	—	cpe:2.3:o:microsoft:windows_server_2012:-:::::::*
microsoft	windows_server_2012	r2	cpe:2.3:o:microsoft:windows_server_2012:r2:::::::*
microsoft	windows_server_2016	—	cpe:2.3:o:microsoft:windows_server_2016:-:::::::*
microsoft	windows_server_2016	20h2	cpe:2.3:o:microsoft:windows_server_2016:20h2:::::::*
microsoft	windows_server_2016	2004	cpe:2.3:o:microsoft:windows_server_2016:2004:::::::*
microsoft	windows_server_2019	—	cpe:2.3:o:microsoft:windows_server_2019:-:::::::*

References for CVE-2021-31962

URL	Tags
http://packetstormsecurity.com/files/163206/Windows-Kerberos-AppContainer-Enterprise-Authentication-Capability-Bypass.html	Third Party Advisory VDB Entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31962	Patch Vendor Advisory

URL

CVE-2021-31962 | Kerberos AppContainer Security Feature Bypass Vulnerability

Exploit prediction scoring system (EPSS) score for CVE-2021-31962

Common vulnerability scoring system (CVSS) metrics for CVE-2021-31962

Weakness enumeration for CVE-2021-31962

Affected software / configurations for CVE-2021-31962

References for CVE-2021-31962