feat(security): action-posture Security dashboard with exploit intel and triage (#1424)

* feat(security): reframe masthead as action posture, not worst-CVE severity

Derive the Security masthead from an action posture (Action needed /
Monitoring / Secure / Unknown) instead of raw scanner severity, and label
the raw Critical/High counts as scanner detections. "Secure" now means
nothing is actionable right now, never a claim that no vulnerabilities
exist; Unknown covers a missing scanner or a node with no completed scan.

Phase-1 bootstrap: "actionable" is approximated from the overview facts
that already exist (fixable findings, secrets, misconfigs); a later phase
moves the bucketing to the backend.

* feat(security): derive overview action posture from triaged facts

Add deriveSecurityPosture as the single bucketing function and extend
/security/overview with posture facts (fixableCriticalHigh, dangerousCompose,
accepted, rawCritical/rawHigh, plus knownExploited/publiclyExposed placeholders
that later phases populate) and the derived posture verb.

Suppression- and acknowledgement-aware counts come from one bounded read-time
pass over the latest-scan Critical/High findings, grouped per image so the
existing read-time filters apply unchanged. The pass is capped and flags
posturePartial, so a large node degrades gracefully instead of scanning every
detail row. The masthead now prefers the backend posture and keeps the local
bootstrap only as a fallback for older remote nodes reached through the proxy.

* feat(security): capture Trivy finding enrichment (status, CVSS, vendor, purl, layer)

parseTrivyOutput now keeps the per-finding fields Trivy already returns and we
previously discarded: Status (fixed / will_not_fix / end_of_life / ...), CVSS
(score + vector, preferring the NVD source then falling back), vendor severity,
package URL, package path, and layer digest. Persisted on vulnerability_details
via additive nullable columns (guarded ALTER), bound null when absent, and
carried through the cached-scan reconstruction path.

These fields separate scary from exploitable and feed the action posture and the
per-finding evidence tags. Field paths verified against Trivy's documented
image-scan JSON; covered by parse and insert/read round-trip tests.

* feat(security): add CVE exploit-intel service (CISA KEV + FIRST EPSS)

Add CveIntelService, a daily background cache of CISA KEV membership and FIRST
EPSS scores stored in a new cve_intel table and joined to findings at read time
by CVE id (never frozen onto scan rows, so a CVE entering KEV later lights up on
scans already stored). EPSS is fetched only for CVE ids present in stored
findings, batched; both feeds are best-effort and keep the last cache on
failure, so the Security page degrades gracefully offline. Wired into
startup/shutdown like the other background services.

The overview now counts known-exploited Critical/High findings, and KEV
membership escalates posture to Action needed even when no fix is available.

A per-instance "Exploit intelligence" toggle on the scanner setup surface lets
air-gapped or firewalled hosts disable the outbound fetch; the daily tick keeps
running but skips the fetch body when it is off.

* feat(security): show per-finding evidence tags (KEV, EPSS, vendor status, CVSS)

The vulnerabilities endpoint joins read-time exploit intel (KEV membership and
EPSS score) onto each finding by CVE id, and the scan sheet renders evidence
tags beside each CVE: known-exploited, EPSS probability, vendor will-not-fix /
end-of-life, and the CVSS score. Severity becomes one signal among several so an
operator can tell scary from exploitable, with no invented composite score.

* feat(security): evolve CVE suppressions into triage decisions

Layer a triage status and optional OpenVEX justification onto CVE suppressions.
Statuses: needs review / affected / not affected / accepted risk / fixed / false
positive / ignored. Dismissing states (not affected, accepted, fixed, false
positive, ignored) stop a finding from driving the action posture; needs review
and affected stay actionable and are surfaced as counts. Existing rows default
to "accepted" (the prior suppress behavior), so nothing changes for them.

The overview now reports needsReview / notAffected / accepted as distinct facts
derived from the triage status. The decision replicates across the fleet
(snapshot + replicated-insert carry status + justification) so a replica's
posture matches the control node. The inline suppress dialog gains a triage
decision selector; the read-time filter surfaces the status and justification on
every finding.

* feat(security): export fleet triage decisions as OpenVEX (Admiral)

Add an OpenVEX exporter that turns the instance's CVE triage decisions into a
standard VEX document (not_affected / fixed / affected / under_investigation,
with justifications), and a GET /security/vex/export endpoint to download it.
Authoring fleet VEX is a governance capability, so it is gated to Admiral (paid)
plus admin, mirroring the SARIF export gate; the Suppressions panel shows an
Export VEX action only on Admiral.

* docs(security): document action posture, evidence tags, exploit intel, and triage

Update the Security page and CVE suppressions docs for the action-posture
masthead (scanner detections vs product posture), per-finding evidence tags
(KEV / EPSS / CVSS / vendor status), the exploit-intelligence toggle (CISA KEV +
FIRST EPSS) on scanner setup, triage decisions layered on suppressions, and
OpenVEX export of fleet triage decisions.

* test(security): match intel hosts exactly in CveIntelService test

Route the fetch stub and its call assertions by exact hostname
(www.cisa.gov / api.first.org) instead of a domain substring check.
Resolves the js/incomplete-url-substring-sanitization code-scanning
alerts on the test's URL routing; behavior is unchanged.

frontend/src/components/settings/SuppressionsPanel.tsx

@@ -6,12 +6,13 @@ import { Badge } from '@/components/ui/badge';
 import { Skeleton } from '@/components/ui/skeleton';
 import { ScrollArea } from '@/components/ui/scroll-area';
 import { Modal, ModalHeader, ModalBody, ModalFooter, ConfirmModal } from '@/components/ui/modal';
-import { ChevronLeft, ChevronRight, Plus, Trash2 } from 'lucide-react';
+import { ChevronLeft, ChevronRight, Plus, Trash2, Download } from 'lucide-react';
 import { toast } from '@/components/ui/toast-store';
 import { apiFetch } from '@/lib/api';
 import { FleetTabHeading } from '@/components/fleet/FleetEmptyState';
 import type { CveSuppression } from '@/types/security';
 import { useAuth } from '@/context/AuthContext';
+import { useLicense } from '@/context/LicenseContext';
 
 const CVE_ID_RE = /^(CVE-\d{4}-\d{4,}|GHSA-[\w-]{14,})$/;
 const PAGE_SIZE = 8;
@@ -38,6 +39,7 @@ interface SuppressionsPanelProps {
 
 export function SuppressionsPanel({ isReplica }: SuppressionsPanelProps) {
   const { isAdmin } = useAuth();
+  const { isPaid } = useLicense();
   const [rows, setRows] = useState<CveSuppression[]>([]);
   const [loading, setLoading] = useState(true);
   const [dialogOpen, setDialogOpen] = useState(false);
@@ -148,6 +150,24 @@ export function SuppressionsPanel({ isReplica }: SuppressionsPanelProps) {
     return d.toLocaleDateString();
   };
 
+  const handleExportVex = useCallback(async () => {
+    try {
+      const res = await apiFetch('/security/vex/export', { localOnly: true });
+      if (!res.ok) throw new Error('Failed to export VEX');
+      const blob = await res.blob();
+      const url = URL.createObjectURL(blob);
+      const a = document.createElement('a');
+      a.href = url;
+      a.download = 'sencho-fleet.openvex.json';
+      document.body.appendChild(a);
+      a.click();
+      a.remove();
+      URL.revokeObjectURL(url);
+    } catch (err) {
+      toast.error((err as Error)?.message || 'Failed to export VEX');
+    }
+  }, []);
+
   return (
     <div className="space-y-4">
       <FleetTabHeading
@@ -155,10 +175,18 @@ export function SuppressionsPanel({ isReplica }: SuppressionsPanelProps) {
         subtitle="Accept known-benign CVEs so they stop triggering alerts. Suppressions apply at read time across the fleet and never modify stored scan data."
         action={
           isAdmin && !isReplica ? (
-            <Button size="sm" onClick={openCreate}>
-              <Plus className="w-4 h-4 mr-1.5" />
-              Add suppression
-            </Button>
+            <div className="flex items-center gap-2">
+              {isPaid && (
+                <Button size="sm" variant="outline" onClick={handleExportVex}>
+                  <Download className="w-4 h-4 mr-1.5" />
+                  Export VEX
+                </Button>
+              )}
+              <Button size="sm" onClick={openCreate}>
+                <Plus className="w-4 h-4 mr-1.5" />
+                Add suppression
+              </Button>
+            </div>
           ) : undefined
         }
       />

frontend/src/components/settings/__tests__/SuppressionsPanel.test.tsx

@@ -28,6 +28,10 @@ vi.mock('@/context/AuthContext', () => ({
   useAuth: () => ({ isAdmin: true }),
 }));
 
+vi.mock('@/context/LicenseContext', () => ({
+  useLicense: () => ({ isPaid: false }),
+}));
+
 import { apiFetch } from '@/lib/api';
 import { toast } from '@/components/ui/toast-store';
 import { SuppressionsPanel } from '../SuppressionsPanel';