An argument injection flaw in the diff scan operation of AWS security‑agent‑mcp‑server enables malicious actors to supply a crafted reference value that causes the service to create, overwrite, or truncate files on the host system outside the prescribed workspace directory. This allows an attacker to write arbitrary content or delete critical files, potentially compromising system integrity and confidentiality.

All installations of AWS security‑agent‑mcp‑server older than version 0.2.0 are impacted. The vulnerability is specific to the diff scan functionality exposed by the service and affects any environment where the agent is running with permissions to write to the host file system.

The CVSS score of 6.9 indicates a moderate risk. The EPSS metric is not available, and the vulnerability is not listed in the CISA KEV catalog. The likely attack vector depends on the exposure of the diff scan operation; if the operation is accessible remotely or can be triggered by an adversary with code execution capability on the host, the flaw could be exploited to create or modify files. The CWE identifiers (CWE‑73 and CWE‑88) reflect external control of file names and argument injection, underscoring the need for input validation and privilege confinement.