Here’s a simple, practical way to make **release gates** that auto‑decide if a build is “routine” or “risky” by comparing the *semantic delta* across SBOMs, VEX data, and dependency graphs—so product managers can approve (or defer) with evidence, not guesswork.

### What this means (quick background)

* **SBOM**: a bill of materials for your build (what components you ship).
* **VEX**: vendor statements about whether known CVEs actually affect a product/version.
* **Dependency graph**: how components link together at build/runtime.
* **Semantic delta**: not just “files changed,” but “risk‑relevant meaning changed” (e.g., new reachable vuln path, new privileged capability, downgraded VEX confidence).

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### The gate’s core signal (one line)

**Risk Verdict = f(ΔSBOM, ΔReachability, ΔVEX, ΔConfig/Capabilities, ΔExploitability)** → Routine | Review | Block

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### Minimal data you need per release

* **SBOM (CycloneDX/SPDX)** for previous vs current release.
* **Reachability subgraph**: which vulnerable symbols/paths are actually callable (source, package, binary, or eBPF/runtime).
* **VEX claims** merged from vendors/distros/internal (with trust scores).
* **Policy knobs**: env tier (prod vs dev), allowed unknowns, max risk budget, critical assets list.
* **Exploit context**: EPSS/CISA KEV or your internal exploit sighting, if available.

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### How to compute the semantic delta (fast path)

1. **Component delta**: new/removed/updated packages → tag each change with severity (critical/security‑relevant vs cosmetic).
2. **Vulnerability delta**:

   * New CVEs introduced?
   * Old CVEs now mitigated (patch/backport) or declared **not‑affected** via VEX?
   * Any VEX status regressions (e.g., “not‑affected” → “under‑investigation”)?
3. **Reachability delta**:

   * Any *new* call‑paths to vulnerable functions?
   * Any risk removed (path eliminated via config/feature‑flag/off by default)?
4. **Config/capabilities delta**:

   * New container perms (NET_ADMIN, SYS_ADMIN), new open ports, new outbound calls.
   * New data flows to sensitive stores.
5. **Exploitability delta**:

   * EPSS/KEV jumps; active exploitation signals.

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### A tiny, useful scoring rubric (defaults you can ship)

* Start at 0. Add:

  * +6 if any **reachable** critical vuln (no valid VEX “not‑affected”).
  * +4 if any **reachable** high vuln.
  * +3 if new sensitive capability added (e.g., NET_ADMIN) or new public port opened.
  * +2 if VEX status regressed (NA→U/I or Affected).
  * +1 per unknown package origin or unsigned artifact (cap at +5).
* Subtract:

  * −3 per *proven* mitigation (valid VEX NA with trusted source + reachability proof).
  * −2 if vulnerable path is demonstrably gated off in target env (feature flag off + policy evidence).
* Verdict:

  * **0–3** → Routine (auto‑approve)
  * **4–7** → Review (PM/Eng sign‑off)
  * **≥8** → Block (require remediation/exception)

*(Tune thresholds per env: e.g., prod stricter than staging.)*

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### What PMs see (clean UI)

* **Badge**: Routine / Review / Block.
* **Why** (3–5 bullets):

  * “Added `libpng` 1.6.43 (new), CVE‑XXXX reachable via `DecodePng()`”
  * “Vendor VEX for `libssl` says not‑affected (function not built)”
  * “Container gained `CAP_NET_RAW`”
* **Evidence buttons**:

  * “Show reachability slice” (mini graph)
  * “Show VEX sources + trust”
  * “Show SBOM diff”
* **Call to action**:

  * “Auto‑remediate to 1.6.44” / “Mark exception” / “Open fix PR”

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### Exception workflow (auditable)

* Exception must include: scope, expiry, compensating controls, owner, and linked evidence (reachability/VEX).
* Gate re‑evaluates each release; expired exceptions auto‑fail the gate.

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### How to wire it into CI/CD (quick recipe)

1. Generate SBOM + reachability slice for `prev` and `curr`.
2. Merge VEX from vendor/distro/internal with trust scoring.
3. Run **Delta Evaluator** → score + verdict + evidence bundle (JSON + attestation).
4. Gate policy checks score vs environment thresholds.
5. Publish an **OCI‑attached attestation** (DSSE/in‑toto) so auditors can replay: *same inputs → same verdict*.

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### Starter policy you can copy

* **Prod**: block on any reachable Critical; review on any reachable High; unknowns ≤ 2; no new privileged caps without exception.
* **Pre‑prod**: review on reachable High/Critical; unknowns ≤ 5.
* **Dev**: allow but flag; collect evidence.

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### Why this helps immediately

* PMs get **evidence‑backed** green/yellow/red, not CVE walls.
* Engineers get **actionable deltas** (what changed that matters).
* Auditors get **replayable proofs** (deterministic verdicts + inputs).

If you want, I can turn this into a ready‑to‑drop spec for Stella Ops (modules, JSON schemas, attestation format, and a tiny React panel mock) so your team can implement the gate this sprint.