MITM in AWS CLI v1/<1.45.28 & v2/<2.35.3: EMR SSH Helper key exchange w/o auth
CVE-2026-18654 Published on August 3, 2026
Disabled SSH host key verification in Amazon AWS CLI EMR helper 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.
Vulnerability Analysis
CVE-2026-18654 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Type
Key Exchange without Entity Authentication
The software performs a key exchange with an actor without verifying the identity of that actor. Performing a key exchange will preserve the integrity of the information sent between two entities, but this will not guarantee that the entities are who they claim they are. This may enable an attacker to impersonate an actor by modifying traffic between the two entities. Typically, this involves a victim client that contacts a malicious server that is impersonating a trusted server. If the client skips authentication or ignores an authentication failure, the malicious server may request authentication information from the user. The malicious server can then use this authentication information to log in to the trusted server using the victim's credentials, sniff traffic between the victim and trusted server, etc.
Products Associated with CVE-2026-18654
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Affected Versions
aws-cli:- Before and including 1.45.27 is affected.
- Before and including 2.35.2 is affected.