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Fencer Vulns
high 7.7

CVE-2021-1638 json

Windows Bluetooth Security Feature Bypass Vulnerability

published 2021-01-12 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-7105

cvss
7.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.2%
EPSS 1.2% chance of exploitation in 30 days, percentile 69%
public exploits
0
none known

Summary

Microsoft is aware of the "Impersonation in the Passkey Entry Protocol" vulnerability. For more information regarding the vulnerability, please see this statement from the Bluetooth SIG. To address the vulnerability, Microsoft has released a software update that will fail attempts to pair if the remote device exchanges a public key with the same X coordinate as the locally exchanged public key

Exploit prediction

1.23% chance of exploitation in the next 30 days, higher than 69% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.7 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C
CNA 3.1 7.7 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CNA 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
NVD 2.0 2.1 AV:L/AC:L/Au:N/C:P/I:N/A:N

Affected products

  • Microsoft Windows 10 Version 20H2
  • Microsoft Windows Server version 20H2
  • Microsoft Windows 10 Version 1803
  • Microsoft Windows 10 Version 1809
  • Microsoft Windows Server 2019
  • Microsoft Windows Server 2019 (Server Core installation)
  • Microsoft Windows 10 Version 1909
  • Microsoft Windows Server, version 1909 (Server Core installation)
  • Microsoft Windows 10 Version 2004
  • Microsoft Windows Server version 2004

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.