GitHub Actions Checkout Now Blocks Risky pull_request_target Checkouts

GitHub has released actions/checkout v7 with enhanced security measures to mitigate risks associated with privileged workflows executing code from untrusted pull requests. This update aims to address a long-standing vulnerability where workflows, particularly those using pull_request_target, could inadvertently run malicious code with elevated privileges, leading to potential unauthorized access to repository secrets. The new default behavior blocks unsafe fork checkouts unless explicitly allowed, marking a significant step in tightening GitHub Actions' default security posture. While this change addresses a critical attack vector, it does not cover all potential vulnerabilities, such as those introduced through custom scripts or other actions, and requires maintainers to remain vigilant when configuring workflows that involve package installations or run privileged operations. This update follows prior efforts by GitHub to enhance security and highlights the need for continuous review and cautious handling of workflows that combine privileged triggers with untrusted code execution.