CVE-2021-45100

Name: CVE-2021-45100
Creator: NVD / NIST
Published: 2021-12-16T05:15:08.827+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 0.91%

Last modified Jun 17, 2026

CVE-2021-45100 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. The ksmbd server through 3.4.2, as used in the Linux kernel through 5.15.8, sometimes communicates in cleartext even though encryption has been enabled. This occurs because it sets the SMB2_GLOBAL_CAP_ENCRYPTION flag when using the SMB 3.1.1 protocol, which is a violation of the SMB protocol specification. EPSS estimates a 0.91% chance of exploitation in the next 30 days.

Description

The ksmbd server through 3.4.2, as used in the Linux kernel through 5.15.8, sometimes communicates in cleartext even though encryption has been enabled. This occurs because it sets the SMB2_GLOBAL_CAP_ENCRYPTION flag when using the SMB 3.1.1 protocol, which is a violation of the SMB protocol specification. When Windows 10 detects this protocol violation, it disables encryption.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

0.91%

55.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-319

Affected Software

Vendor	Product	Versions
Ksmbd Project	Ksmbd	<= 3.4.2
Netapp	H410c Firmware	All versions
Netapp	H300s Firmware	All versions
Netapp	H500s Firmware	All versions
Netapp	H700s Firmware	All versions
Netapp	H300e Firmware	All versions
Netapp	H500e Firmware	All versions
Netapp	H700e Firmware	All versions
Netapp	H410s Firmware	All versions

References

https://github.com/cifsd-team/ksmbd/issues/550Third Party Advisory
https://github.com/cifsd-team/ksmbd/pull/551Patch, Third Party Advisory
https://marc.info/?l=linux-kernel&m=163961726017023&w=2Third Party Advisory
https://security.netapp.com/advisory/ntap-20220107-0001/Third Party Advisory
https://github.com/cifsd-team/ksmbd/issues/550Third Party Advisory
https://github.com/cifsd-team/ksmbd/pull/551Patch, Third Party Advisory
https://marc.info/?l=linux-kernel&m=163961726017023&w=2Third Party Advisory
https://security.netapp.com/advisory/ntap-20220107-0001/Third Party Advisory

Timeline

Published: Dec 16, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-45100?

How severe is CVE-2021-45100?

CVE-2021-45100 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.91% probability of exploitation in the next 30 days.

How do I fix CVE-2021-45100?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-45100?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST