🛡️ Sentinel: [CRITICAL] DSN Redaction Vulnerability Fix

[seonghobae]

🚨 Severity: CRITICAL
💡 Vulnerability: DSNs without standard :// scheme delimiters (e.g. postgres:user:password@host/db) caused urllib.parse.urlsplit to leave netloc empty and put credentials in the path, resulting in the _password_candidates_from_dsn function failing to extract and redact the password.
🎯 Impact: If a driver error occurs with a scheme-less DSN, the unredacted password could be leaked in error messages.
🔧 Fix: Added a fallback condition elif ":" in dsn: within _password_candidates_from_dsn to prepend a dummy http:// scheme when :// is not present. This allows urlsplit to properly extract the netloc and password. Also added a test case test_dsn_lacking_slashes_redacts_secrets to verify this behavior.
✅ Verification: Run cd backend && uv run pytest tests/test_dsn_redaction.py to verify all redaction tests pass successfully.

---

PR created automatically by Jules for task 3087333512911131216 started by @seonghobae

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.

[Copilot]

Pull request overview

Fixes a critical backend security issue where DSN passwords could leak in driver error messages when the DSN lacks the standard :// delimiter, by improving _password_candidates_from_dsn parsing so password/query secrets can still be detected and redacted.

Changes:

• Add a scheme-less DSN fallback that injects a dummy scheme to make urlsplit extract netloc/password.
• Add a regression test covering redaction for postgres:user:...@host/... DSNs without ://.
• Document the incident/learning in .jules/sentinel.md.

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 1 comment.

File	Description
backend/app/dsn_redaction.py	Enhances DSN parsing fallback so password candidates can be extracted even when :// is missing.
backend/tests/test_dsn_redaction.py	Adds a regression test ensuring scheme-less DSNs still redact secrets.
.jules/sentinel.md	Records the DSN redaction bypass and prevention guidance.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (1)

backend/app/dsn_redaction.py:53

• The new scheme-less DSN fallback unconditionally drops everything before the first ':' (when netloc is empty). That fixes postgres:user:pass@host/db, but it breaks another common scheme-less form user:pass@host/db: the fallback turns it into http://pass@host/db, so the password is no longer parsed/extracted and may leak in driver error messages.

            if "://" in dsn:
                # ponytail: keep urlsplit; only swap the non-RFC scheme so userinfo parses.
                parsed = urlsplit("http://" + dsn.split("://", 1)[1])
            elif ":" in dsn:
                parsed = urlsplit("http://" + dsn.split(":", 1)[1])