Report CSP Violations to a Collector Endpoint
Add a report-uri to the Content-Security-Policy header so browser violations are collected and triaged as security events.
Task
Implement Content-Security-Policy: default-src 'self'; report-uri /csp-report to close a known attack surface before the next security review finds it.
When to use this
A penetration test report flags the missing Content-Security-Policy: default-src 'self'; report-uri /csp-report as a medium-severity finding on a public endpoint.
Prerequisites
- A running application with the vulnerable endpoint
- Access to security headers or middleware config
Steps
1. Configure Content-Security-Policy: default-src 'self'; report-uri /csp-report in the project configuration file with the recommended defaults.
Content-Security-Policy: default-src 'self'; report-uri /csp-report
Expected output: The configuration is accepted and Content-Security-Policy: default-src 'self'; report-uri /csp-report runs without errors on the first invocation.
2. Run the check locally to verify Content-Security-Policy: default-src 'self'; report-uri /csp-report produces the expected result before pushing.
pnpm test
Expected output: Local run matches CI behavior; no surprises after push.
3. Add the gate to the CI pipeline so Content-Security-Policy: default-src 'self'; report-uri /csp-report blocks merge on failure.
- name: Run add csp violation reporting
run: pnpm test
Expected output: Pull requests with failing Content-Security-Policy: default-src 'self'; report-uri /csp-report are blocked from merging.
Troubleshooting
Problem
The check passes locally but fails in CI
Solution
Pin dependency versions and the runtime to match CI exactly; reproduce with the same Docker image or act.
Problem
Configuration is rejected with a schema error
Solution
Check the tool version matches the config schema; older versions may not support newer fields.
Limitations
- The gate only runs on events that trigger the workflow; locally pushed commits bypass it.
- Configuration drift is possible if someone edits settings outside version control.
Close the attack surface
Start by measuring the problem. Add a report-uri to the Content-Security-Policy header so browser violations are collected and triaged as security events. The most common mistake is adding the gate without first confirming it catches the issue you care about. Run Content-Security-Policy: default-src ‘self’; report-uri /csp-report against the current codebase and inspect the output before wiring it into CI.
Content-Security-Policy: default-src 'self'; report-uri /csp-reportVerify and monitor
Once the gate is in place, make failures actionable. A failing Content-Security-Policy: default-src ‘self’; report-uri /csp-report should point to the exact file and line, not a generic error. Pin the tool version in the lockfile so a upstream release does not silently change behavior. Review the gate output in every pull request just like a test result.