CVE-2021-31205
published 2021-05-11CVE-2021-31205: Windows SMB Client Security Feature Bypass Vulnerability
PriorityP336medium6.5CVSS 3.1
AVNACLPRNUIRSUCHINAN
EPSS
2.91%
85.4th percentile
Windows SMB Client Security Feature Bypass Vulnerability
Affected
15 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| microsoft | windows_10 | — | — |
| microsoft | windows_10 | — | — |
| microsoft | windows_10_version_2004 | >= 10.0.0 < 10.0.19041.982 | 10.0.19041.982 |
| microsoft | windows_10_version_20h2 | >= 10.0.0 < 10.0.19042.982 | 10.0.19042.982 |
| microsoft | windows_server_2016 | — | — |
| microsoft | windows_server_2016 | — | — |
| microsoft | windows_server_version_2004 | >= 10.0.0 < 10.0.19041.982 | 10.0.19041.982 |
| microsoft | windows_server_version_20h2 | >= 10.0.0 < 10.0.19042.982 | 10.0.19042.982 |
| msrc | windows_10_version_2004_for_32-bit_systems | — | — |
| msrc | windows_10_version_2004_for_arm64-based_systems | — | — |
| msrc | windows_10_version_2004_for_x64-based_systems | — | — |
| msrc | windows_10_version_20h2_for_32-bit_systems | — | — |
| msrc | windows_10_version_20h2_for_arm64-based_systems | — | — |
| msrc | windows_server_version_2004 | — | — |
| msrc | windows_server_version_20h2 | — | — |
CVSS provenance
nvdv3.16.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
nvdv2.04.3MEDIUMAV:N/AC:M/Au:N/C:P/I:N/A:N
vendor_msrc6.5MEDIUM
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Microsoft
Windows SMB Client Security Feature Bypass Vulnerability
vendor_msrc·2021-05-11·CVSS 6.5
CVE-2021-31205 [MEDIUM] Windows SMB Client Security Feature Bypass Vulnerability
Windows SMB Client Security Feature Bypass Vulnerability
FAQ: What kind of security feature could be bypassed by successfully exploiting this vulnerability?
Guest fallback access in SMB2 is not disabled by default. Installing this security update will disable guest fallback access to enforce the operating system edition settings and Group Policy settings. Guest fallback behavior default will return matching previously documented settings.
Alternatively, customers can manually disable guest access by configuring this registry value:
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters] "AllowInsecureGuestAuth"=dword:0
For more information on guest fallback access behaviors and default settings, refer to:
Guest access in SMB2 disabled by default in Windows
Win
GHSA
GHSA-7h4c-m77c-qp3c: Windows SMB Client Security Feature Bypass Vulnerability
ghsa_unreviewed·2022-05-24
CVE-2021-31205 [MEDIUM] GHSA-7h4c-m77c-qp3c: Windows SMB Client Security Feature Bypass Vulnerability
Windows SMB Client Security Feature Bypass Vulnerability
No detection rules found.
No public exploits indexed.
2021-05-11
Published