ci: gate on known advisories in the .NET dependency tree (RB-14)

npm audit --omit=dev gates the shipped frontend bundle; nothing equivalent existed for the backend, so the entire .NET dependency tree — direct and transitive — was unscanned (BIO-016 lists it first under "Absent"). The ticket's literal wording would not have worked. `dotnet list package --vulnerable` is a reporting command: it prints the advisory table and exits 0 regardless. Verified with a throwaway project on System.Net.Http 4.3.0 — severity High, GHSA-7jgj-8wvc-jh57, exit code 0. A bare `- run: dotnet list package --vulnerable` would have added a line that reads like coverage in a compliance review and enforces nothing, which is worse than leaving the gap visible. scripts/dotnet-audit.sh runs the scan and matches "has the following vulnerable packages" — the exact sentence dotnet prints per project on a hit. One script, two callers (ci.yml and ci-local.sh), so the workflow and the local gate cannot drift apart. No severity threshold and no suppression list: picking either before a real advisory forces the question would be guessing at a policy nobody needs yet. Secret scanning, BIO-016's other named absence, stays on the checklist. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-08-27 16:24:16 +02:00
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+# RB-14 — scan the .NET dependency tree for known advisories
+
+Status: **implemented** · 2026-08-27 · Source findings: `07-bio2-compliance.md` BIO-016 · `99-backlog.md` RB-14
+
+## What was wrong
+
+`npm audit --omit=dev` gates the shipped frontend bundle. Nothing equivalent existed for the
+backend, so **the entire .NET dependency tree — direct and transitive — was unscanned.** BIO-016
+lists it first under "Absent".
+
+## The trap the ticket walked into
+
+The backlog row says: `dotnet list package --vulnerable --include-transitive` **as a failing
+step**. Implemented literally, that step cannot fail. `dotnet list package --vulnerable` is a
+_reporting_ command: it prints the advisory table and exits 0 regardless.
+
+Verified rather than assumed — a throwaway project with `System.Net.Http 4.3.0`:
+
+```
+Project `vulntest` has the following vulnerable packages
+   > System.Net.Http   4.3.0   4.3.0   High   https://github.com/advisories/GHSA-7jgj-8wvc-jh57
+EXITCODE=0
+```
+
+A **High** severity advisory, exit code **0**. A bare `- run: dotnet list package --vulnerable`
+would have added a line to `ci.yml` that reads like coverage in a compliance review and enforces
+nothing — which is worse than leaving the gap visible.
+
+## What changed
+
+| File                       | Change                                                                     |
+| -------------------------- | -------------------------------------------------------------------------- |
+| `scripts/dotnet-audit.sh`  | **new** — runs the scan, matches its output, exits 1 on a hit              |
+| `.github/workflows/ci.yml` | new backend step calling the script (same `changes.outputs.backend` guard) |
+| `scripts/ci-local.sh`      | new `backend dependency audit` step calling the same script                |
+
+**One script, two callers**, rather than the same four lines pasted into a workflow and a shell
+script that would then drift. The guard matches `has the following vulnerable packages` — the
+exact sentence `dotnet list` prints per project on a hit; the clean case prints
+`has no vulnerable packages given the current sources` instead.
+
+## Verification
+
+- Against the real solution: passes, both projects clean (exit 0).
+- Against the marker sentence `dotnet list` actually emits: the guard fires and exits 1.
+- The exit-0-on-High behaviour that motivates the whole script is reproduced above.
+
+## Residual
+
+`--include-transitive` means a vulnerable package pulled in by a dependency turns CI red with no
+direct upgrade available. The fix in that case is a direct `PackageReference` pinning a patched
+version; the script's failure message says so. There is deliberately **no severity threshold and
+no suppression list** — adding one before a real advisory forces the question would be guessing
+at a policy nobody has needed yet.
+
+Secret scanning (gitleaks/trufflehog), BIO-016's other named absence, is **not** in this ticket
+and remains on the pre-production checklist.