CVE-2021-38173

Name: CVE-2021-38173
Creator: NVD / NIST
Published: 2021-08-07T19:15:06.997+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 3.16%

Last modified Jun 17, 2026

CVE-2021-38173 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. Btrbk before 0.31.2 allows command execution because of the mishandling of remote hosts filtering SSH commands using ssh_filter_btrbk.sh in authorized_keys.. EPSS estimates a 3.16% chance of exploitation in the next 30 days.

Description

Btrbk before 0.31.2 allows command execution because of the mishandling of remote hosts filtering SSH commands using ssh_filter_btrbk.sh in authorized_keys.

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

3.16%

86.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-77

Affected Software

Vendor	Product	Versions
Digint	Btrbk	< 0.31.2
Debian	Debian Linux	9.0
Fedoraproject	Fedora	34
Fedoraproject	Fedora	35

References

https://github.com/digint/btrbk/blob/master/ChangeLogRelease Notes, Third Party Advisory
https://github.com/digint/btrbk/commit/58212de771c381cd4fa05625927080bf264e9584Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/09/msg00002.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BP2T32JMENJFRP2HWXR7FTTZVRTTPECL/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LM7GLTUN5YS4KE2RNBX732EAMVVGNEX3/
https://github.com/digint/btrbk/blob/master/ChangeLogRelease Notes, Third Party Advisory
https://github.com/digint/btrbk/commit/58212de771c381cd4fa05625927080bf264e9584Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/09/msg00002.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BP2T32JMENJFRP2HWXR7FTTZVRTTPECL/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LM7GLTUN5YS4KE2RNBX732EAMVVGNEX3/

Timeline

Published: Aug 7, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-38173?

Btrbk before 0.31.2 allows command execution because of the mishandling of remote hosts filtering SSH commands using ssh_filter_btrbk.sh in authorized_keys.

How severe is CVE-2021-38173?

CVE-2021-38173 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 3.16% probability of exploitation in the next 30 days.

How do I fix CVE-2021-38173?

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-2021-38173?

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

Scan your code now

Source: NVD / NIST