CVE-2026-18654: Key exchange without entity authentication in the EMR SSH helper commands in Amazon AWS CLI before 1.45.28 and

Routine

MEDIUM 6.8REMOTEWATCHLISTUPGRADE

CVE-2026-18654 is a medium-severity flaw (CVSS 6.8) affecting aws command line interface. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	6.8 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 79%)
CISA exploited list	No
Weakness	CWE-322
Published	2026-08-03
Last modified	2026-10-23

Publisher (CNA): AMZN · Vendor: amazon

Last updated 2026-10-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-03 20:17 UTCPublished CVE record published
2026-10-23 21:10 UTCUpdated Record last modified

amazon aws command line interface UPGRADE

Affected: < 1.45.28 · >= 2.0.0 and < 2.35.3

Fixed in: 1.45.28, 2.35.3

Safe to downgrade to: a release before 2.0.0

1. Check installed version

apt-cache policy aws-command-line-interface || rpm -q aws-command-line-interface || aws-command-line-interface --version

2. UPGRADE to 1.45.28 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade aws-command-line-interface

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade aws-command-line-interface

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.0.0 (Debian / Ubuntu)

apt-cache madison aws-command-line-interface sudo apt install aws-command-line-interface=<VERSION_BEFORE_2.0.0> sudo apt-mark hold aws-command-line-interface

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list aws-command-line-interface sudo dnf downgrade aws-command-line-interface-<VERSION_BEFORE_2.0.0> sudo dnf versionlock add aws-command-line-interface

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

Python (pip) · awscli · FIXED · 1.45.28 · vulnerable: <= 1.45.27 · source

pip install --upgrade "awscli>=1.45.28" pip show awscli

Fedora ELN · ntpd-rs · FIXED · 1.7.2-3.eln159 · FEDORA-2026-57e4a99310 · source

sudo dnf upgrade --advisory=FEDORA-2026-57e4a99310

Fedora 46 · moby-engine · FIXED · 29.9.2-2.fc46 · FEDORA-2026-4856be87b3 · source

sudo dnf upgrade --advisory=FEDORA-2026-4856be87b3

RHEL 10 · awscli2 · DEFERRED

RHEL 7 · awscli · DEFERRED

RHEL 8 · awscli · DEFERRED

RHEL 9 · awscli2 · DEFERRED

RHEL 9 · fence-agents · DEFERRED

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-3133 · source

sudo dnf update --advisory=ALAS2023-2026-3133

Amazon Linux 2 · see advisory · FIXED · ALAS2-2026-3966 · source

sudo yum update --advisory=ALAS2-2026-3966

Advisories and coverage

Official advisories

Amazon Linux 2 ALAS: ALAS2-2026-3966 (medium): awscli 2026-10-12
Amazon Linux 2 ALAS: ALAS2AWSCLI1-2026-001 (medium): awscli 2026-10-12
Amazon Linux 2023 ALAS: ALAS2023-2026-3133 (medium): awscli-2 2026-09-29

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-18654?

aws command line interface: upgrade to 1.45.28, 2.35.3. Exact commands for each OS are on this page.

Is CVE-2026-18654 being exploited?

CVE-2026-18654 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-18654 affect?

CVE-2026-18654 affects aws command line interface. Severity is medium (CVSS 6.8). 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 position

How urgent is CVE-2026-18654?

Priority 39/100. Remotely exploitable, no login, no user action; On your watchlist

Software pages

AWS vulnerabilities

Related CVEs

CVE-2026-13769 MEDIUM 5.5 UPGRADE Overly permissive file permissions in AWS CLI before 1.44.78 (v1) and 2.34.29 (v2) on Unix-like systems where

References

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