Command Injection Risk in AWS Bedrock AgentCore Python SDK Install Routine
Unsanitised arguments in the package installer could let authenticated users run arbitrary code inside the managed sandbox environment.
Key points
- AWS released version 1.18.1 to fix CVE-2026-16796.
- The flaw affects versions prior to 1.18.1 of the bedrock-agentcore SDK.
- Attackers must be authenticated and able to supply crafted package names.
The AWS Bedrock AgentCore Python SDK contains a vulnerability in its package installation routine. The issue, tracked as CVE-2026-16796, involves improper neutralisation of argument delimiters. This flaw might allow a remote authenticated user to execute arbitrary commands within the Code Interpreter sandbox by supplying crafted package name arguments to the install_packages() method.
Root cause
The vulnerability is described as improper neutralisation of argument delimiters in the install_packages() method. The source material does not provide further technical details on the specific failure mechanism or how the delimiters are mishandled beyond this classification.
Attack path
An attacker requires valid authentication to the AWS Bedrock service. The vulnerability might allow execution of arbitrary commands via crafted package name arguments passed to the install_packages() method. The source material does not specify additional prerequisites or steps required for exploitation beyond providing these crafted arguments.
Affected versions
- bedrock-agentcore versions earlier than 1.18.1 are vulnerable to this issue.
- Version 1.18.1 includes the necessary fixes and addresses the improper neutralisation.
- Any forked or derivative code based on vulnerable versions may also be affected.
Mitigation
- Upgrade the bedrock-agentcore SDK to version 1.18.1 or later immediately.
- If upgrading is not possible, avoid passing untrusted or model-generated input to the install_packages() function.
- Validate dynamic package names against strict PyPI naming rules before calling the SDK.
- Constrain any extras groups to comma-separated identifiers to limit potential exploitation vectors.
Signals worth monitoring
Security teams should monitor for unusual command executions within sandboxed environments, particularly those originating from package installation routines. Look for processes spawned by the Code Interpreter client that do not match expected library installation patterns. Check for attempts to access system binaries or network resources from within the sandbox. If anomalies are detected, isolate the affected sandbox instance and review the input logs for crafted package names containing special characters or unexpected delimiters.
What to do and how to stay safe: AWS
- Inventory all deployments using the bedrock-agentcore Python SDK and verify their current version numbers.
- Implement strict input validation for any package names derived from external or dynamic sources.
- Monitor sandbox processes for unexpected command executions or deviations from standard library installation behaviour.
- Review access controls to ensure only authorised users can trigger package installations in the Code Interpreter.
Step-by-step guide: Out-of-band patches: what small businesses need to know
General security guidance from the Firewall Pulse newsroom. It is not confirmed advice from the organisations named in this story.
Frequently asked questions
What is the severity of CVE-2026-16796?
The AWS security bulletin classifies the issue as "Important" and notes it requires attention.
Who discovered this vulnerability?
Sergio Garcia and BeyondTrust Phantom Labs identified the flaw and collaborated with AWS on the disclosure.
Is there a fix available for the vulnerability?
Yes, AWS has addressed the issue in bedrock-agentcore version 1.18.1, which users are advised to upgrade to.
