[plan] Fix template injection vulnerabilities from static analysis

[github-actions]

Overview

This tracking issue covers fixing template injection vulnerabilities discovered in the December 4, 2024 static analysis scan using zizmor.

Source: Discussion #5510

Security Impact

The scan identified 3 template injection vulnerabilities across our agentic workflows:

• 1 HIGH severity issue in cloclo workflow (High confidence)
• 2 INFORMATIONAL issues in changeset and stale-repo-identifier workflows (Low confidence)

Template injection vulnerabilities can allow attackers to execute arbitrary code in GitHub Actions runners, potentially leading to:

• Execution of malicious commands
• Exfiltration of secrets and credentials
• Compromise of the CI/CD pipeline
• Unauthorized repository modifications

Planned Tasks

1. Fix HIGH severity template injection in cloclo workflow - Immediate priority
2. Fix INFORMATIONAL template injection in changeset workflow - Follow-up
3. Fix INFORMATIONAL template injection in stale-repo-identifier workflow - Follow-up
4. Add template injection prevention guidelines to documentation - Best practices
5. Integrate zizmor security scanning into CI/CD pipeline - Prevention

Security Best Practice

The fix follows GitHub's security hardening guidelines: move untrusted ${{ ... }} expressions to the env: block and reference them as environment variables ($VAR_NAME) in shell scripts.

Success Criteria

• All template injection findings resolved
• Re-scan with zizmor confirms fixes
• No functional regressions in affected workflows
• Documentation updated with prevention guidelines
• Automated scanning prevents future issues

AI generated by Plan Command for discussion #5510