CVE-2026-4269 Amazon CVE debrief

Who should care

Teams using the Bedrock AgentCore Starter Toolkit before v0.1.13, especially if they built the toolkit after 2025-09-24 or rely on artifacts produced by those builds. Build and platform owners should care most because the issue affects the supply/build path rather than a typical runtime-only deployment.

Technical summary

NVD describes the weakness as a missing S3 ownership verification in the Bedrock AgentCore Starter Toolkit. The vulnerable CPE range ends before 0.1.13. The result is a remote code-injection opportunity during the build process, with possible downstream code execution in the AgentCore Runtime. NVD associates the issue with CWE-283 and CWE-340 and lists a CVSS 4.0 vector that includes network access, high attack complexity, and user interaction.

Defensive priority

Medium priority overall, but high urgency for any environment that matches the affected build/version window because the impact is code execution in the build supply chain.

Recommended defensive actions

• Upgrade Bedrock AgentCore Starter Toolkit to v0.1.13 or later.
• Identify whether any builds were run after 2025-09-24 on versions earlier than v0.1.13.
• Review build pipelines and generated artifacts for affected toolkit versions and rebuild after upgrading.
• Use trusted ownership and integrity controls for any S3-based build inputs or dependencies.
• Track the AWS security bulletin and release notes for any additional remediation guidance.

Evidence notes

This debrief is based on the supplied NVD record and vendor references. The NVD metadata lists the vulnerable version range as versions before 0.1.13 and cites AWS security bulletin 2026-008 and the v0.1.13 release notes. The supplied description narrows the affected population to users who built after September 24, 2025. No exploit details beyond the provided build-time injection and code execution impact are included.

Official resources