What is CVE-2026-18654?

CVE-2026-18654 is a medium-severity security vulnerability in awscli (pip), affecting versions <= 1.45.27. It is fixed in 1.45.28.

How severe is CVE-2026-18654?

CVE-2026-18654 has a CVSS score of 6.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Which versions of awscli are affected by CVE-2026-18654?

awscli (pip) versions <= 1.45.27 is affected.

Is there a fix for CVE-2026-18654?

Yes. CVE-2026-18654 is fixed in 1.45.28. Upgrade to this version or later.

Is CVE-2026-18654 exploitable, and should I be worried?

Whether CVE-2026-18654 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

What actually determines whether CVE-2026-18654 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

How do I fix CVE-2026-18654?

Upgrade awscli to 1.45.28 or later.

CVE-2026-18654 in awscli

Q: How severe is CVE-2026-18654?

CVE-2026-18654 has a CVSS score of 6.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Q: Which versions of awscli are affected by CVE-2026-18654?

awscli (pip) versions <= 1.45.27 is affected.

Q: Is there a fix for CVE-2026-18654?

Yes. CVE-2026-18654 is fixed in 1.45.28. Upgrade to this version or later.

Q: Is CVE-2026-18654 exploitable, and should I be worried?

Whether CVE-2026-18654 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

Q: What actually determines whether CVE-2026-18654 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

Q: How do I fix CVE-2026-18654?

Upgrade awscli to 1.45.28 or later.

Summary

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

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.

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 or directly via email to [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.

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

CVE-2026-18654 has a CVSS score of 6.8 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.45.28); upgrading removes the vulnerable code path.

Affected versions

awscli (<= 1.45.27)

Security releases

awscli → 1.45.28 (pip)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

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.

Frequently Asked Questions

What is CVE-2026-18654? CVE-2026-18654 is a medium-severity security vulnerability in awscli (pip), affecting versions <= 1.45.27. It is fixed in 1.45.28.
How severe is CVE-2026-18654? CVE-2026-18654 has a CVSS score of 6.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
Which versions of awscli are affected by CVE-2026-18654? awscli (pip) versions <= 1.45.27 is affected.
Is there a fix for CVE-2026-18654? Yes. CVE-2026-18654 is fixed in 1.45.28. Upgrade to this version or later.
Is CVE-2026-18654 exploitable, and should I be worried? Whether CVE-2026-18654 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
What actually determines whether CVE-2026-18654 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
How do I fix CVE-2026-18654? Upgrade awscli to 1.45.28 or later.