CVE-2021-3634

mediumpriority · track · 28EPSS 0.047 · 92 %ileDEEURUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

4.68% (92nd) EPSS

CVSS 4 · medium

Is it mine?

69 products

Check your exposure

Who says so?

5 sources

cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-27

A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared secrets during the lifetime of the session. One of them is called secret_hash and the other session_id. Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked as long as these buffers were same. But the key re-exchange operation can also change the key exchange method, which can be based on hash of different size, eventually creating "secret_hash" of different size than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used again during second key re-exchange.

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

Fixedlibssh-0:0.9.6-3.el8.aarch64 as a component of Red Hat Enterprise Linux BaseOS (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-0:0.9.6-3.el8.i686 as a component of Red Hat Enterprise Linux BaseOS (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-0:0.9.6-3.el8.ppc64le as a component of Red Hat Enterprise Linux BaseOS (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-0:0.9.6-3.el8.s390x as a component of Red Hat Enterprise Linux BaseOS (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-0:0.9.6-3.el8.src as a component of Red Hat Enterprise Linux BaseOS (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-0:0.9.6-3.el8.x86_64 as a component of Red Hat Enterprise Linux BaseOS (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-config-0:0.9.6-3.el8.noarch as a component of Red Hat Enterprise Linux BaseOS (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debuginfo-0:0.9.6-3.el8.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debuginfo-0:0.9.6-3.el8.aarch64 as a component of Red Hat Enterprise Linux BaseOS (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debuginfo-0:0.9.6-3.el8.i686 as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debuginfo-0:0.9.6-3.el8.i686 as a component of Red Hat Enterprise Linux BaseOS (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debuginfo-0:0.9.6-3.el8.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debuginfo-0:0.9.6-3.el8.ppc64le as a component of Red Hat Enterprise Linux BaseOS (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debuginfo-0:0.9.6-3.el8.s390x as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debuginfo-0:0.9.6-3.el8.s390x as a component of Red Hat Enterprise Linux BaseOS (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debuginfo-0:0.9.6-3.el8.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debuginfo-0:0.9.6-3.el8.x86_64 as a component of Red Hat Enterprise Linux BaseOS (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debugsource-0:0.9.6-3.el8.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debugsource-0:0.9.6-3.el8.aarch64 as a component of Red Hat Enterprise Linux BaseOS (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debugsource-0:0.9.6-3.el8.i686 as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debugsource-0:0.9.6-3.el8.i686 as a component of Red Hat Enterprise Linux BaseOS (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debugsource-0:0.9.6-3.el8.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debugsource-0:0.9.6-3.el8.ppc64le as a component of Red Hat Enterprise Linux BaseOS (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debugsource-0:0.9.6-3.el8.s390x as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debugsource-0:0.9.6-3.el8.s390x as a component of Red Hat Enterprise Linux BaseOS (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debugsource-0:0.9.6-3.el8.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-debugsource-0:0.9.6-3.el8.x86_64 as a component of Red Hat Enterprise Linux BaseOS (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-devel-0:0.9.6-3.el8.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-devel-0:0.9.6-3.el8.i686 as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-devel-0:0.9.6-3.el8.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-devel-0:0.9.6-3.el8.s390x as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031
Fixedlibssh-devel-0:0.9.6-3.el8.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing these updated packages, all running applications using libssh must be restarted for this update to take effect.
https://access.redhat.com/errata/RHSA-2022:2031

cvss

Technical severity, 0–10. One row per scoring source.

6.5

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–medium · 3.5–6.5

v2.04mediumAV:N/AC:L/Au:S/C:N/I:N/A:Pprimary · NVD / NIST USexploitability 8 · impact 2.9

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 2.8 · impact 3.6

v3.16.5mediumAV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:Hsecondary · FSTEC (BDU) RU

v3.16mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)

v3.13.5lowCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:Lsecondary · Red Hat Product Security US

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-787USprimaryCWE-119USCWE-787USCWE-787US

affected products (69)

Products and version ranges known to be affected.

Dell PowerProtect Data Domainall versionscert_bundDEcpe:/a:dell:powerprotect_data_domain:-
Dell PowerProtect Data Domain <7.10.1.40all versionscert_bundDE
Dell PowerProtect Data Domain <7.13.1.10all versionscert_bundDE
Dell PowerProtect Data Domain <7.7.5.50all versionscert_bundDE
Dell PowerProtect Data Domain <8.1.0.0all versionscert_bundDE
Dell PowerProtect Data Domain Management Centerall versionscert_bundDEcpe:/a:dell:powerprotect_data_domain_management_center:-
Dell PowerProtect Data Domain OSall versionscert_bundDEcpe:/o:dell:powerprotect_data_domain_os:-
SUSE Linuxall versionscert_bundDEcpe:/o:suse:suse_linux:-
Dell PowerProtect Data Domain< 7.10.1.40cert_bundDE
Dell PowerProtect Data Domain< 7.13.1.10cert_bundDE
Dell PowerProtect Data Domain< 7.7.5.50cert_bundDE
Dell PowerProtect Data Domain< 8.1.0.0cert_bundDE
n/a libssh≤ libssh 0.9.6enisa_euvdEU
Canonical Ltd. Ubuntu≤ 21.10fstec_bduRU
Canonical Ltd. Ubuntu≤ 20.04fstec_bduRU
Fedora Project Fedora≤ 35fstec_bduRU
Fedora Project Fedora≤ 34fstec_bduRU
Fedora Project Fedora≤ 33fstec_bduRU
IBM Corp. IBM Robotic Process Automation≤ 21.0.3fstec_bduRU
Red Hat Inc. Red Hat Enterprise Linux≤ 8fstec_bduRU

showing 20 of 69

advisories (3)

Vendor and ecosystem advisories describing this.

RHSA-2022:2031Red Hat Security Advisory: libssh security, bug fix, and enhancement update2022-05-10csaf · redhat_csafUS
An update for libssh is now available for Red Hat Enterprise Linux 8. Red Hat Product Security has rated this update as having a security impact of Low. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.
WID-SEC-W-2022-0001libssh: Schwachstelle ermöglicht Umgehen von SicherheitsvorkehrungenDeutsch2021-08-26csaf · cert_bundDE
Ein entfernter, authentisierter Angreifer kann eine Schwachstelle in libssh ausnutzen, um Sicherheitsvorkehrungen zu umgehen.
WID-SEC-W-2024-3377Dell PowerProtect Data Domain: Mehrere SchwachstellenDeutsch2024-11-07csaf · cert_bundDE
Ein lokaler Angreifer kann mehrere Schwachstellen in Dell PowerProtect Data Domain ausnutzen, um seine Privilegien zu erhöhen, Informationen offenzulegen und um nicht näher beschriebene Auswirkungen zu erzielen.

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu cert_bund redhat_csaf NVD CVE.org MITRE

published 2021-08-31modified 2026-06-17

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+16119 more

references (70)

External citations — patches, advisories, analysis.

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