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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
None
No data modification
Availability
None
No disruption
CVSS Vector v4.0
Weakness Type (CWE)
References 3
https://aws.amazon.com/security/security-bulletins/2026-107-aws/
ff89ba41-3aa1-4d27-914a-91399e9639e5
https://github.com/aws/amazon-ssm-agent/releases/tag/3.3.4851.0
ff89ba41-3aa1-4d27-914a-91399e9639e5
https://github.com/aws/amazon-ssm-agent/security/advisories/GHSA-w9jw-h72g-6hxc
ff89ba41-3aa1-4d27-914a-91399e9639e5