Path traversal in the aws:downloadContent plugin in amazon-ssm-agent

Bulletin ID: 2026-091-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 08/28/2026 11:00 AM PDT Description: AWS Systems Manager Agent (amazon-ssm-agent) is Amazon software that runs on Amazon Elastic Compute Cloud (Amazon EC2) instances, edge devices, on-premises servers, and virtual machines (VMs). Amazon-ssm-agent makes it possible for Systems Manager to update, manage, and configure these resources. We identified CVE-2026-81849, where an improper limitation of a pathname to a restricted directory in the aws:downloadContent plugin in amazon-ssm-agent before 3.3.4515.0 might allow an authenticated remote user whose ssm:SendCommand permission is restricted to the AWS-DownloadContent document, to write arbitrary files outside the intended download directory with root privileges, via crafted object keys in the S3 source the document is directed to retrieve. This issue may lead to arbitrary code execution as root if specific sensitive files are overwritten. To remediate this issue, customers should upgrade amazon-ssm-agent to version 3.3.4515.0 or later. Impacted versions: Amazon amazon-ssm-agent from 2.0.767.0 to 3.3.4364.0 Please refer to the article below for the most up-to-date and complete information related to this AWS Security Bulletin.