Live › vulnerability › GHSA-w9jw-h72g-6hxc
Go to dashboardThe AWS Systems Manager Agent on managed nodes fails to validate equivalent address forms in Session Manager remote-host port forwarding, so the denylist can be bypassed. An authenticated user with port-forwarding permission can reach link-local endpoints and obtain the instance's temporary IAM role credentials.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-24 19:28 UTC. All times on this page are UTC.
Any managed node running SSM Agent older than 3.3.4851.0 that supports Session Manager remote-host port forwarding, including EC2 instances and on-premises servers. Exposure requires an principal allowed to start port-forwarding sessions to remote hosts; teams that restrict those permissions have less exposure.
No product ranges from the sources yet.
amazon-ssm-agent -version on Linux or the agent version in Windows installed programs.ssm:StartSession with the AWS-StartPortForwardingSessionToRemoteHost document.3.3.4851.0 or later on all managed nodes.ssm:StartSession and SSM document permissions so untrusted principals cannot start remote-host port-forwarding sessions.The fix above is the answer. These hold the line until you can deploy it, and are the only option on lines that get no fix.
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CVE-2026-89049 - Server-side request forgery in the Session Manager port forwarding functionality in AWS Systems Manager Agent
Bulletin ID: 2026-107-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 09/10/2026 11:30 AM PDT
Description:
AWS Systems Manager Agent (SSM Agent) is software that runs on managed nodes (EC2 instances, on-premises servers, and other supported machines) and processes requests from the AWS Systems Manager service, enabling capabilities including Session Manager port forwarding to remote hosts. We identified CVE-2026-89049, a server-side request forgery issue in the remote-host port forwarding functionality. Due to improper validation of equivalent address representations, an authenticated user with port-forwarding permission could bypass the remote destination denylist and reach link-local endpoints, potentially obtaining the managed instance's temporary IAM role credentials and acting with that role's permissions from outside the instance.
Impacted versions: < 3.3.4851.0 (all versions supporting remote-host port forwarding)
Resolution:
This issue has been addressed in SSM Agent version 3.3.4851.0. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.
Workarounds:
Until the agent is upgraded, restrict use of the AWS-StartPortForwardingSessionToRemoteHost document by scoping ssm:StartSession IAM permissions and SSM document permissions so that untrusted principals cannot start remote-host port-forwarding sessions.
References:
Please email [email protected] with any security questions or concerns.
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