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.

CVE-2026-81849 is a path traversal vulnerability (CWE-22) in the aws:downloadContent plugin of amazon-ssm-agent versions prior to 3.3.4515.0. An authenticated remote user with restricted ssm:SendCommand permissions limited to the AWS-DownloadContent document can exploit crafted S3 object keys to write arbitrary files outside the intended download directory with root privileges. This could lead to arbitrary code execution as root if sensitive system files are overwritten. The vulnerability requires the attacker to already have some level of AWS IAM access, reducing but not eliminating the risk. Amazon has issued a security bulletin and released a patched version. Remediation requires upgrading amazon-ssm-agent to version 3.3.4515.0 or later. The issue affects AWS Systems Manager managed instances across all platforms running the vulnerable agent version.