CVE-2026-4295
CVSS 7.8 HIGH: improper trust boundary enforcement in Kiro IDE before version 0.8.0 on all supported platforms might allow a remote… EPSS 0.2% (12th percentile).
Vulnerabilities & Exploits
Bedrock AgentCore Starter Toolkit builds before v0.1.13 omitted S3 ownership verification. That omission can let a remote actor inject code during the build and cause code execution in the AgentCore Runtime for builds performed after Sept 24, 2025. Separately, AWS API MCP Server versions >=0.2.14 and <1.3.9 have a no-access/workdir path bypass that can expose arbitrary local files to MCP clients.
1 source · Mar 17
CVSS 7.8 HIGH: improper trust boundary enforcement in Kiro IDE before version 0.8.0 on all supported platforms might allow a remote… EPSS 0.2% (12th percentile).
AWS Security Bulletins
Arbitrary code execution via crafted project files in Kiro IDE
We identified CVE-2026-4295, where improper trust boundary enforcement allowed arbitrary code execution when a user opened a maliciously crafted project directory.</p> <p><b>Impacted versions:</b> < 0.8.0</p> <p><b>Please refer to the article below for the most up-to-date and complete information related to this AWS Security Bulletin.</b></p>
originalAWS Security Bulletins
CVE-2026-4269 - Improper S3 ownership verification in Bedrock AgentCore Starter Toolkit
<p><b>Bulletin ID:</b> 2026-008-AWS<br/> <b>Scope:</b> AWS<br/> <b>Content Type:</b> Important (requires attention)<br/> <b>Publication Date:</b> 2026/03/16 11:15 AM PDT</p> <p><b>Description:</b></p> <p>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.</p> <p><b>Impacted versions:</b> All versions of Bedrock AgentCore Starter Toolkit versions before v0.1.13.
originalAWS Security Bulletins
CVE-2026-4270 - AWS API MCP File Access Restriction Bypass
By default, file operations are restricted to a designated working directory (workdir), but this can be configured to allow unrestricted file system access (unrestricted) or to block all local file path arguments entirely (no-access).</p> <p>We identified CVE-2026-4270: Improper Protection of Alternate Path exists in the no-access and workdir feature of the AWS API MCP Server versions >= 0.2.14 and < 1.3.9 on all platforms may allow the bypass of intended file access restriction and expose arbitrary local file contents in the MCP client application context.</p> <p><b>Impacted versions:</b> awslabs.aws-api-mcp-server >= 0.2.14, < 1.3.9</p> <p><b>Please refer to the article below for the most up-to-date and complete information related to this AWS Security Bulletin.</b></p>
originalPart of the PlainSec briefing for 2026-03-18
Every edition of this story: Tooling flaws allow build-time code execution and file exposure