CVE-2026-89049
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Server-Side Request Forgery in AWS Systems Manager Agent

Publication date: 2026-09-10

Last updated on: 2026-09-10

Assigner: AMZN

Description
A server-side request forgery issue due to improper validation of equivalent address representations in the port forwarding to remote hosts functionality in Amazon AWS Systems Manager Agent (SSM Agent) before 3.3.4851.0 on all platforms might allow an authenticated remote user to bypass the remote destination denylist and reach link-local endpoints, potentially obtaining the temporary IAM role credentials of a managed instance and acting with that role's permissions from outside the instance, via a crafted destination host value that uses an alternate representation of a denied link-local address. To remediate this issue, users should upgrade to version 3.3.4851.0 or later.

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Meta Information

Published
2026-09-10
Last Modified
2026-09-10
Generated
2026-09-10
AI Q&A
2026-09-10
EPSS Evaluated
N/A
NVD
CVE-2026-89049
EUVD
EUVD-2026-75674

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
amazon aws_systems_manager_agent 3.3.4851.0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-1289 The product receives an input value that is used as a resource identifier or other type of reference, but it does not validate or incorrectly validates that the input is equivalent to a potentially-unsafe value.
CWE-918 The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

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Executive Summary

This is a server-side request forgery (SSRF) vulnerability in AWS Systems Manager Agent (SSM Agent) before version 3.3.4851.0. It allows an authenticated remote user with port-forwarding permissions to bypass the denylist that blocks access to link-local addresses. By exploiting improper validation of equivalent address representations, the attacker can reach link-local endpoints like the Instance Metadata Service and obtain the instance's temporary IAM role credentials. These credentials can be used from outside the instance to perform actions permitted by the role's IAM policy.

Detection Guidance

Detecting this vulnerability requires checking the version of SSM Agent installed on your systems. Use the command 'amazon-ssm-agent --version' on Linux or check the installed program version in Windows. If the version is below 3.3.4851.0, the system is vulnerable. Additionally, review IAM policies for any misuse of the AWS-StartPortForwardingSessionToRemoteHost document.

Impact Analysis

An attacker could gain access to sensitive temporary IAM role credentials of a managed instance. This allows them to perform actions on AWS services as if they were the instance itself, potentially leading to data breaches, unauthorized resource access, or other malicious activities depending on the role's permissions. The impact includes compromised confidentiality, integrity, and availability of AWS resources.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating compliance requirements such as GDPR (data protection) or HIPAA (health information privacy). Unauthorized access to IAM credentials may result in data breaches, which are reportable under these regulations, potentially leading to legal penalties, fines, or reputational damage.

Mitigation Strategies

Immediately upgrade SSM Agent to version 3.3.4851.0 or later. If upgrading is not possible, restrict the use of the AWS-StartPortForwardingSessionToRemoteHost document via IAM permissions to prevent unauthorized port forwarding.

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