AWS Systems Manager

AWS Systems Manager Agent Flaw Allows Bypass of Port Forwarding Restrictions

Amazon has fixed a vulnerability in the AWS Systems Manager agent that permits an authenticated attacker to bypass restrictions on port forwarding sessions. The issue, tracked as CVE-2026-89049, stems from inadequate validation of equivalent representations of blocked link-local addresses. As a result, attackers can reach the EC2 instance metadata service at 169.254.169.254 and obtain temporary credentials tied to the instance's IAM role. Affected versions are those prior to 3.3.4851.0, with the fix included in that release and all subsequent versions. AWS recommends reviewing custom builds of the agent, restricting access to the AWS-StartPortForwardingSessionToRemoteHost document, auditing Session Manager activity, and applying least-privilege principles to IAM roles.

Critical SSRF Vulnerability in AWS SSM Agent Allows IAM Credential Theft via Port Forwarding Bypass

Amazon Web Services has disclosed a high-severity server-side request forgery vulnerability in the AWS Systems Manager Agent. The flaw, tracked as CVE-2026-89049, affects the port forwarding feature used by Session Manager and stems from insufficient validation that permits bypass of deny-list restrictions on link-local addresses. Successful exploitation requires port-forwarding permissions but can lead to unauthorized access to instance metadata and temporary IAM role credentials. The company rated the issue as Important with CVSSv4.0 base score 8.5 and CVSSv3.1 score 9.9. The vulnerability was addressed in version 3.3.4851.0 released on 13 July 2026, prior to the public advisory issued on 10 September 2026.