Vulnerability · Published Mar 16, 2026 · Assigned by AMZN
CVE-2026-4269Improper S3 ownership verification in Bedrock AgentCore Starter Toolkit
High 7.5
In plain English
A high-severity security flaw in Bedrock AgentCore Starter Toolkit from AWS. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 17% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
A missing S3 ownership verification in the Bedrock AgentCore Starter Toolkit before version v0.1.13 may allow a remote actor to inject code during the build process, leading to code execution in the AgentCore Runtime. This issue only affects users of the Bedrock AgentCore Starter Toolkit before version v0.1.13 who build or have built the Toolkit after September 24, 2025. Any users on a version >=v0.1.13, and any users on previous versions who built the toolkit before September 24, 2025 are not affected. To remediate this issue, customers should upgrade to version v0.1.13.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | bedrock-agentcore-starter-toolkit | 0.1.13 | GHSA-xfhr-q72q-jcrj |
| PyPI | bedrock-agentcore-starter-toolkit | 0.1.13 | PYSEC-2026-2396 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| AWS | Bedrock AgentCore Starter Toolkit | 0.1.0 – before 0.1.13 |
Weakness: CWE-340, CWE-283 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H