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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| AWS | Amazon SSM Agent | < 3.3.4851.0 | 3.3.4851.0 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | amazon-ssm-agent | 3.3.5226.0-1.amzn2023 | ALAS2023-2026-3149 |
| Amazon Linux 2 | amazon-ssm-agent | 3.3.5226.0-1.amzn2 | ALAS2-2026-3963 |
Advisories 2
- ALAS2-2026-3963 Critical: amazon-ssm-agent security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Sep 30, 2026
- ALAS2023-2026-3149 Critical: amazon-ssm-agent security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Sep 30, 2026