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Full vulnerability report · 2026
CVE-2026-18654High confidence

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

AWS · aws-cli

6.9MediumCVSS 4.0
Recommended action
Patch only the product branches with a verified fix

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority. Verified remediation exists for at least one product or source, but 61 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:Medium, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 0.29% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs AWS aws-cli and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: As exposure requiresRemediation target: Within 365 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 61 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Open-source package ranges2 source-attributed ranges

These OSV and GitHub advisory ranges apply only to the named package and ecosystem. A listed fixed version is not a universal product patch or proof that an update is installed.

Ecosystem and packageAffected rangeFirst fixed versionEvidence
PyPIawscliECOSYSTEM: introduced 0; fixed 1.45.281.45.28OSV record ↗aggregator derived · 10 Sep 2026
pipawscli<= 1.45.271.45.28GitHub advisory ↗upstream repository advisory · 6 Aug 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2026-18654 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityaws-cli: AWS CLI: Information disclosure due to disabled SSH host key verification
61 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • awscli2.src as a component of Red Hat Enterprise Linux 10
  • awscli.src as a component of Red Hat Enterprise Linux 7
  • awscli.src as a component of Red Hat Enterprise Linux 8
  • awscli2.src as a component of Red Hat Enterprise Linux 9
  • fence-agents-aliyun as a component of Red Hat Enterprise Linux 9
  • fence-agents-all as a component of Red Hat Enterprise Linux 9
  • fence-agents-amt-ws as a component of Red Hat Enterprise Linux 9
  • fence-agents-apc as a component of Red Hat Enterprise Linux 9
  • fence-agents-apc-snmp as a component of Red Hat Enterprise Linux 9
  • fence-agents-aws as a component of Red Hat Enterprise Linux 9
  • fence-agents-azure-arm as a component of Red Hat Enterprise Linux 9
  • fence-agents-bladecenter as a component of Red Hat Enterprise Linux 9
Summary
A flaw was found in AWS CLI. This vulnerability, located in the Elastic MapReduce (EMR) Secure Shell (SSH) helper commands, involves a lack of entity authentication during key exchange. A remote attacker, positioned between the client and the EMR cluster, could exploit this to intercept SSH sessions and file transfers, leading to information disclosure.
Remediation
Users who do not run the `aws emr ssh`, `aws emr socks`, `aws emr put`, or `aws emr get` subcommands are not exposed. Where these subcommands are required, verify the EMR node's SSH host key out-of-band before connecting, or restrict their use to trusted networks where a machine-in-the-middle attacker cannot intercept traffic. Upgrading to awscli 1.45.28 or later (v1 line) or awscli2 2.35.3 or later (v2 line) removes the vulnerable behavior.
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-52415

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch only the product branches with a verified fix

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority. Verified remediation exists for at least one product or source, but 61 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

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.

What

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

The product performs a key exchange with an actor without verifying the identity of that actor.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

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

The product performs a key exchange with an actor without verifying the identity of that actor.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Key Exchange without Entity Authentication → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
High: exploitation depends on specific conditions
Security boundary
Not a CVSS 4.0 base metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-322 ↗

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

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
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

Common Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.ATPresentAttack requirements: A particular deployment or execution condition must be present.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCNoneVulnerable-system confidentiality: No direct loss is represented by this metric.VINoneVulnerable-system integrity: No direct loss is represented by this metric.VANoneVulnerable-system availability: No direct loss is represented by this metric.SCHighSubsequent-system confidentiality: A successful attack can cause a major loss.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-322
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

Cyber Security Agency of Singapore · English · CSA-SB-20260805Security Bulletin 5 Aug 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 5 Aug 2026, published on 5 August 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Fix availability varies by product
Affected
Fixed
An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
Action
Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
Workaround
Users who do not run the `aws emr ssh`, `aws emr socks`, `aws emr put`, or `aws emr get` subcommands are not exposed. Where these subcommands are required, verify the EMR node's SSH host key out-of-band before connecting, or restrict their use to trusted networks where a machine-in-the-middle attacker cannot intercept traffic. Upgrading to awscli 1.45.28 or later (v1 line) or awscli2 2.35.3 or later (v2 line) removes the vulnerable behavior.
04

Evidence and provenance

Published 3 Aug 2026 · Last source change 4 Aug 2026, 19:32 UTC · CWE-322 · Key Exchange without Entity Authentication

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2026-52415
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD awaiting enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
ENISA EUVD · EUVD-2026-52415↗Vendor CSAF · Red Hat Product Security↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-18654 · cve.blacktree.nl