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🛡️ CVE-2026-18654 — awscli

🟡 CVSS 6.8 — Medium ✅ No Known Exploit CWE-322 NVD
6.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

AWS CLI: Disabled SSH host key verification in Amazon AWS CLI EMR helper commands

Summary

The AWS Command Line Interface (AWS CLI) is a unified tool to manage AWS services from the command line. An issue exists where the EMR SSH helper commands (aws emr ssh, aws emr socks, aws emr put, aws emr get) passed StrictHostKeyChecking=no to the underlying SSH client, disabling host key verification.

Impact

A network-positioned actor could perform a man-in-the-middle action to intercept SSH sessions and file transfers between the client and EMR cluster instances. Successful exploitation requires the actor to have network access on the path between the client machine and the EMR cluster endpoint. This could result in full visibility of commands executed, files transferred, and credentials passed over the SSH session.

Impacted versions: AWS CLI v1 <= 1.45.27, AWS CLI v2 <= 2.35.2

Patches

This issue has been addressed in AWS CLI v1 version 1.45.28 and AWS CLI v2 version 2.35.3. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.

Workarounds

There is no workaround. The insecure SSH option was hardcoded and could not be overridden by the user.

References

If you have any questions or comments about this advisory, we ask that you contact AWS Security via our [vulnerability reporting page](https://aws.amazon.com/security/vulnerability-reporting) or directly via email to [[email protected]](mailto:[email protected]). Please do not create a public GitHub issue.

Acknowledgement

We would like to thank Ali Sunbul for collaborating on this issue through the coordinated vulnerability disclosure process.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is changed, meaning a successful attack can affect components beyond the vulnerable one. Rated impact: confidentiality high, integrity none, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: High — the attacker first has to win a race, learn a secret or otherwise prepare the target.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Changed — a successful attack reaches components beyond the vulnerable one.
  • Confidentiality impact: High — total loss, or loss the attacker controls.
  • Integrity impact: None.
  • Availability impact: None.

Weakness class

CVE-2026-18654 is classified as CWE-322: Key Exchange without Entity Authentication. The product performs a key exchange with an actor without verifying the identity of that actor.

Affected software

CVE-2026-18654 is recorded against 2 packages.

  • awscli (fixed in 1.45.28)
  • unknown

Timeline and source

Published on 6 August 2026 and last revised on 15 August 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com (Web)
nvd.nist.gov (Advisory)
aws.amazon.com (Web)
github.com (Package)
github.com (Web)
github.com (Web)

Other advisories for this package

awscli has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-322: Key Exchange without Entity Authentication) in other software:

Details

Severity Medium
CVSS Score 6.8
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N
CWE CWE-322
Public Exploit ✅ No
Source NVD
Published 2026-08-06
Updated 2026-08-20
Modified 2026-08-15
Fix URL N/A

Affected Packages

Software From version Fixed in
awscli — 1.45.28
unknown — —

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