The article explains how .env files work in application development, clarifying that apps read environment variables rather than .env files directly. It discusses security risks of .env file sprawl across systems and proposes alternatives like runtime injection to better manage credentials without relying on .env files.
Miri stored all environment variables in target/, allowing secrets to persist in GitHub Actions caches and potentially be accessed by pull requests. The Rust Security Response Team identified the vulnerability and will fix it in nightly 2026-09-22 by preserving only CARGO_* variables and OUT_DIR.