Description
The client side in OpenSSH 5.7 through 8.4 has an Observable Discrepancy leading to an information leak in the algorithm negotiation. This allows man-in-the-middle attackers to target initial connection attempts (where no host key for the server has been cached by the client). NOTE: some reports state that 8.5 and 8.6 are also affected.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | openssh | No fix yet | — |
| Debian 13 | openssh | No fix yet | — |
| Debian 12 | openssh | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8 | openssh +6 | 8.0p1-10.el8 | RHSA-2021:4368 |
| RHEL 8 | pam_ssh_agent_auth | 0.10.3-7.10.el8 | RHSA-2021:4368 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 8 | openssh-askpass | 8.0p1-10.el8 | ALSA-2021:4368 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 8 | openssh | 8.0p1-10.el8 | RLSA-2021:4368 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP2 | openssh +1 | 8.1p1-5.9.1 | SUSE-SU-2020:3736-1 |
| SLES 15 SP1 | openssh +1 | 7.9p1-6.22.1 | SUSE-SU-2020:3866-1 |
| SLES 15 | openssh | 7.6p1-9.38.1 | SUSE-SU-2020:3882-1 |
| SLES 12 SP5 | openssh +1 | 7.2p2-78.10.1 | SUSE-SU-2020:3844-1 |
| SLES 12 SP4 | openssh +1 | 7.2p2-78.10.1 | SUSE-SU-2020:3844-1 |
Show 15 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP3 | openssh +1 | 7.2p2-74.57.1 | SUSE-SU-2021:0022-1 |
| SLES 12 SP2 | openssh +1 | 7.2p2-74.57.1 | SUSE-SU-2021:0022-1 |
| SLES for SAP 15 | openssh | 7.6p1-9.38.1 | SUSE-SU-2020:3882-1 |
| SLES for SAP 12 SP5 | openssh +1 | 7.2p2-78.10.1 | SUSE-SU-2020:3844-1 |
| SLES for SAP 12 SP4 | openssh +1 | 7.2p2-78.10.1 | SUSE-SU-2020:3844-1 |
| SLES for SAP 12 SP3 | openssh +1 | 7.2p2-74.57.1 | SUSE-SU-2021:0022-1 |
| SLES for SAP 12 SP2 | openssh +1 | 7.2p2-74.57.1 | SUSE-SU-2021:0022-1 |
| SLE HPC 15 | openssh | 7.6p1-9.38.1 | SUSE-SU-2020:3882-1 |
| SUSE OpenStack Cloud Crowbar 9 | openssh +1 | 7.2p2-78.10.1 | SUSE-SU-2020:3844-1 |
| SUSE OpenStack Cloud Crowbar 8 | openssh +1 | 7.2p2-74.57.1 | SUSE-SU-2021:0022-1 |
| SUSE OpenStack Cloud 9 | openssh +1 | 7.2p2-78.10.1 | SUSE-SU-2020:3844-1 |
| SUSE OpenStack Cloud 8 | openssh +1 | 7.2p2-74.57.1 | SUSE-SU-2021:0022-1 |
| SUSE OpenStack Cloud 7 | openssh +1 | 7.2p2-74.57.1 | SUSE-SU-2021:0022-1 |
| SUSE HPE Helion OpenStack 8 | openssh +1 | 7.2p2-74.57.1 | SUSE-SU-2021:0022-1 |
| SUSE Enterprise Storage 5 | openssh +1 | 7.2p2-74.57.1 | SUSE-SU-2021:0022-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 15.2 | openssh +1 | 8.1p1-lp152.4.9.1 | openSUSE-SU-2020:2240-1 |
| openSUSE Leap 15.1 | openssh +1 | 7.9p1-lp151.4.18.1 | openSUSE-SU-2020:2298-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | openssh | 8.4_p1-r0 | — |
| Alpine v3.23 | openssh | 8.4_p1-r0 | — |
| Alpine v3.22 | openssh | 8.4_p1-r0 | — |
| Alpine v3.21 | openssh | 8.4_p1-r0 | — |
| Alpine v3.20 | openssh | 8.4_p1-r0 | — |
Show 8 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | openssh | 8.4_p1-r0 | — |
| Alpine v3.18 | openssh | 8.4_p1-r0 | — |
| Alpine v3.17 | openssh | 8.4_p1-r0 | — |
| Alpine v3.16 | openssh | 8.4_p1-r0 | — |
| Alpine v3.15 | openssh | 8.4_p1-r0 | — |
| Alpine v3.14 | openssh | 8.4_p1-r0 | — |
| Alpine v3.13 | openssh | 8.4_p1-r0 | — |
| Alpine v3.12 | openssh | 8.3_p1-r1 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 8 | openssh +6 | 8.0p1-10.el8 | ELSA-2021-4368 |
| Oracle Linux 8 | pam_ssh_agent_auth | 0.10.3-7.10.el8 | ELSA-2021-4368 |
Advisories 20
- ALSA-2021:4368 Moderate: openssh security update AlmaLinux Security Advisories · Oct 29, 2026
- SSA-398330 SSA-398330: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP >= V3.1.0 and < V3.1.5 Siemens ProductCERT · Oct 13, 2026
- RHSA-2021:4368 Red Hat Security Advisory: openssh security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- RLSA-2021:4368 Moderate: openssh security update Rocky Linux Security Advisories · Feb 5, 2026
- SUSE-SU-2020:3736-1 Security update for openssh SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:3882-1 Security update for openssh SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:3866-1 Security update for openssh SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:3844-1 Security update for openssh SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:2298-1 Security update for openssh SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:2240-1 Security update for openssh SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:0022-1 Security update for openssh SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2023-0068 OpenSSH: Schwachstelle ermöglicht Umgehen von Sicherheitsvorkehrungen BSI CERT-Bund (WID) · Dec 17, 2025
- SCA-2025-0011 Vulnerabilities affecting Endress+Hauser SSG-E210GC SICK PSIRT · Oct 2, 2025
- ICSA-23-348-10 Siemens SIMATIC S7-1500 CISA ICS & IT advisories · Aug 12, 2025
- SCA-2025-0009 Vulnerabilities affecting SICK TDC-E210GC SICK PSIRT · Aug 1, 2025
- WID-SEC-2024-1591 Juniper JUNOS: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 11, 2024
- WID-SEC-2024-1082 Juniper JUNOS: Mehrere Schwachstellen BSI CERT-Bund (WID) · May 9, 2024
- WID-SEC-2023-1969 HPE Fabric OS: Mehrere Schwachstellen ermöglichen Privilegieneskalation BSI CERT-Bund (WID) · Aug 6, 2023
- WID-SEC-2023-1599 IBM Security Guardium: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jun 29, 2023
- ELSA-2021-4368 Moderate: openssh security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Nov 16, 2021
References
- https://github.com/openssh/openssh-portable/compare/V_8_3_P1...V_8_4_P1
- https://www.fzi.de/en/news/news/detail-en/artikel/fsa-2020-2-ausnutzung-eines-informationslecks-fuer-gezielte-mitm-angriffe-auf-ssh-clients/
- https://security.netapp.com/advisory/ntap-20200709-0004/
- [oss-security] 20201202 Some mitigation for openssh CVE-2020-14145 mailing-list
- https://anongit.mindrot.org/openssh.git/commit/?id=b3855ff053f5078ec3d3c653cdaedefaa5fc362d
- https://docs.ssh-mitm.at/CVE-2020-14145.html
- https://github.com/ssh-mitm/ssh-mitm/blob/master/ssh_proxy_server/plugins/session/cve202014145.py
- GLSA-202105-35 vendor-advisory