CVE-2026-18654: AWS CLI Disabled SSH Host Key Verification Vulnerability

MODERATE
Advisory Identifier: GHSA-hqvf-45jj-mccq
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CVSS 6.8
CWE-322
Published
Advisory Summary

CVE-2026-18654 is a MODERATE (CVSS 6.8) disabled ssh host key verification vulnerability (CWE-322: Key Exchange without Entity Authentication) affecting AWS CLI libraries in the PyPI ecosystem. The issue involves disabled ssh host key verification in amazon aws cli emr helper commands. Remediation is available by upgrading affected packages to version 1.45.28.

CVE-2026-18654 at a Glance

CVE Identifier CVE-2026-18654
GHSA Identifier GHSA-hqvf-45jj-mccq
Severity MODERATE
CVSS v3.1 Base Score 6.8
CWE Classification CWE-322: Key Exchange without Entity Authentication
Affected Product AWS CLI
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 6.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Changed (S:C)
Confidentiality High (C:H)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-18654

To remediate this vulnerability, upgrade all affected AWS CLI dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

awscli fixed: 1.45.28 
pip install awscli>=1.45.28
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show awscli

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-18654, inspect your installed packages using pip:

pip show awscli

Analyze the terminal output to locate any version of AWS CLI in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.45.28), your application is affected.

Note: The pip show awscli command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-322: Key Exchange without Entity Authentication, where the product performs a key exchange with an actor without verifying the identity of that actor. In AWS CLI, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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 [aws-security@amazon.com](mailto:aws-security@amazon.com). 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.

CVE-2026-18654 Affected AWS CLI Versions

1 component(s)
Fixed Versions:
1.45.28
Product / Package Ecosystem Affected Versions Fixed Version
awscli
pypi/awscli
PyPI
< 1.45.28
1.45.28

References

NVD — CVE-2026-18654 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-18654
GitHub Advisory / Wiki ADVISORY
https://github.com/aws/aws-cli/security/advisories/GHSA-hqvf-45jj-mccq
AWS CLI Security Information SECURITY
https://aws.amazon.com/security/security-bulletins/2026-071-aws
AWS CLI Source Repository REPOSITORY
https://github.com/aws/aws-cli
AWS CLI Source Repository REPOSITORY
https://github.com/aws/aws-cli/blob/develop/CHANGELOG.rst
AWS CLI Source Repository REPOSITORY
https://github.com/aws/aws-cli/blob/v2/CHANGELOG.rst

Frequently Asked Questions

What is CVE-2026-18654?
CVE-2026-18654 is a security vulnerability in AWS CLI involving Disabled SSH host key verification in Amazon AWS CLI EMR helper commands under CWE-322: Key Exchange without Entity Authentication.
Which AWS CLI versions are affected?
Affected versions include releases prior to 1.45.28 across affected packages: awscli.
What version fixes CVE-2026-18654?
Upgrading to 1.45.28 (or the latest patched release for your respective branch) resolves the vulnerability.
Is awscli affected?
Yes, awscli is affected in releases prior to 1.45.28. Upgrade your dependency to 1.45.28 or later.
What is the CVSS score of CVE-2026-18654?
CVE-2026-18654 has a CVSS v3.1 base score of 6.8 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N.
What CWE is associated with CVE-2026-18654?
CVE-2026-18654 is classified under CWE-322: Key Exchange without Entity Authentication (The product performs a key exchange with an actor without verifying the identity of that actor.).
How can I check PyPI dependencies for CVE-2026-18654?
Run the dependency tree command: 'pip show awscli'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-hqvf-45jj-mccq",
  "modified" : "2026-08-06T20:15:30Z",
  "published" : "2026-08-06T20:15:30Z",
  "aliases" : [ "CVE-2026-18654" ],
  "summary" : "AWS CLI: Disabled SSH host key verification in Amazon AWS CLI EMR helper commands",
  "details" : "### Summary\nThe 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.\n\n### Impact\nA 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.\n\nImpacted versions: AWS CLI v1 <= 1.45.27, AWS CLI v2 <= 2.35.2\n\n### Patches\nThis 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.\n\n### Workarounds\nThere is no workaround. The insecure SSH option was hardcoded and could not be overridden by the user.\n\n### References\nIf 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 [aws-security@amazon.com](mailto:aws-security@amazon.com). Please do not create a public GitHub issue.\n\n### Acknowledgement\nWe would like to thank Ali Sunbul for collaborating on this issue through the coordinated vulnerability disclosure process.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "awscli"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.45.28"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.45.27"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/aws/aws-cli/security/advisories/GHSA-hqvf-45jj-mccq"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-18654"
  }, {
    "type" : "WEB",
    "url" : "https://aws.amazon.com/security/security-bulletins/2026-071-aws"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/aws/aws-cli"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/aws/aws-cli/blob/develop/CHANGELOG.rst"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/aws/aws-cli/blob/v2/CHANGELOG.rst"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-322" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-06T20:15:30Z",
    "nvd_published_at" : "2026-08-03T20:17:17Z"
  }
}