diff --git a/backend/src/__tests__/compose-service.test.ts b/backend/src/__tests__/compose-service.test.ts
index 0c7950e2..aa2443f6 100644
--- a/backend/src/__tests__/compose-service.test.ts
+++ b/backend/src/__tests__/compose-service.test.ts
@@ -958,7 +958,18 @@ describe('ComposeService - idle-output stall backstop', () => {
     process.env.SENCHO_COMPOSE_STALL_TIMEOUT_MS = '1000';
     mockListContainers.mockResolvedValue([]);
     const proc = createMockProcess();
-    mockSpawn.mockReturnValue(proc);
+    // deployStack now spawns a second child (exposure refresh via renderConfig)
+    // after the up command closes. Return the controlled proc for the up spawn,
+    // and a fresh auto-closing proc for the config spawn so the test does not
+    // hang on the already-closed proc.
+    let spawnCount = 0;
+    mockSpawn.mockImplementation(() => {
+      spawnCount += 1;
+      if (spawnCount === 1) return proc;
+      const configProc = createMockProcess();
+      Promise.resolve().then(() => configProc.emit('close', 0));
+      return configProc;
+    });
 
     const svc = ComposeService.getInstance(1);
     // deployStack spawns a single `up`; emit output every 600ms (< 1s window)
@@ -997,7 +1008,16 @@ describe('ComposeService - idle-output stall backstop', () => {
     process.env.SENCHO_COMPOSE_STALL_TIMEOUT_MS = '0'; // invalid → default (10min)
     mockListContainers.mockResolvedValue([]);
     const proc = createMockProcess();
-    mockSpawn.mockReturnValue(proc);
+    // Same pattern as the stall test above: the second spawn (exposure refresh)
+    // needs its own auto-closing proc so deployStack can resolve after close.
+    let spawnCount = 0;
+    mockSpawn.mockImplementation(() => {
+      spawnCount += 1;
+      if (spawnCount === 1) return proc;
+      const configProc = createMockProcess();
+      Promise.resolve().then(() => configProc.emit('close', 0));
+      return configProc;
+    });
 
     const svc = ComposeService.getInstance(1);
     const promise = svc.deployStack('my-stack');
diff --git a/backend/src/__tests__/exposure.test.ts b/backend/src/__tests__/exposure.test.ts
new file mode 100644
index 00000000..132e1406
--- /dev/null
+++ b/backend/src/__tests__/exposure.test.ts
@@ -0,0 +1,305 @@
+import { describe, it, expect } from 'vitest';
+import { deriveStackExposure, buildExposedImageMap, type StackExposure } from '../services/preflight/exposure';
+import type { EffectiveModel } from '../services/preflight/effectiveModel';
+
+function svc(overrides: Record<string, unknown>) {
+  return {
+    name: 'app',
+    image: 'nginx:latest',
+    ports: [] as Array<{ startPort: number; endPort: number; hostIp: string; protocol: string }>,
+    binds: [],
+    namedVolumes: [],
+    storageMounts: [],
+    privileged: false,
+    networkMode: undefined as string | undefined,
+    restart: undefined as string | undefined,
+    hasHealthcheck: false,
+    envKeys: [],
+    networks: [],
+    extraHosts: [],
+    labelKeys: [],
+    ...overrides,
+  };
+}
+
+function model(overrides: Partial<EffectiveModel>): EffectiveModel {
+  return {
+    projectName: 'test',
+    services: [],
+    networks: {},
+    volumes: {},
+    ...overrides,
+  };
+}
+
+const NOW = 1700000000000;
+
+describe('deriveStackExposure', () => {
+  it('marks a service with no ports and no host networking as not exposed', () => {
+    const m = model({ services: [svc({ image: 'nginx:latest' })] });
+    const r = deriveStackExposure(m, 'test', NOW);
+    expect(r.services[0].publiclyExposed).toBe(false);
+    expect(r.services[0].reason).toBeNull();
+  });
+
+  it('marks a service publishing on 0.0.0.0 as exposed', () => {
+    const m = model({
+      services: [
+        svc({
+          ports: [{ startPort: 8080, endPort: 8080, hostIp: '0.0.0.0', protocol: 'tcp' }],
+        }),
+      ],
+    });
+    const r = deriveStackExposure(m, 'test', NOW);
+    expect(r.services[0].publiclyExposed).toBe(true);
+    expect(r.services[0].reason).toBe('published-port');
+    expect(r.services[0].bindings).toEqual(['0.0.0.0:8080/tcp']);
+  });
+
+  it('marks a service publishing on :: (IPv6 all-interfaces) as exposed', () => {
+    const m = model({
+      services: [
+        svc({
+          ports: [{ startPort: 3000, endPort: 3000, hostIp: '::', protocol: 'tcp' }],
+        }),
+      ],
+    });
+    const r = deriveStackExposure(m, 'test', NOW);
+    expect(r.services[0].publiclyExposed).toBe(true);
+  });
+
+  it('marks a service publishing on an empty host IP as exposed (Docker default = all interfaces)', () => {
+    const m = model({
+      services: [
+        svc({
+          ports: [{ startPort: 5432, endPort: 5432, hostIp: '', protocol: 'tcp' }],
+        }),
+      ],
+    });
+    const r = deriveStackExposure(m, 'test', NOW);
+    expect(r.services[0].publiclyExposed).toBe(true);
+  });
+
+  it('marks a service publishing on a specific LAN IP as exposed', () => {
+    const m = model({
+      services: [
+        svc({
+          ports: [{ startPort: 8080, endPort: 8080, hostIp: '192.168.1.50', protocol: 'tcp' }],
+        }),
+      ],
+    });
+    const r = deriveStackExposure(m, 'test', NOW);
+    expect(r.services[0].publiclyExposed).toBe(true);
+  });
+
+  it('keeps a loopback-only service as not exposed', () => {
+    const m = model({
+      services: [
+        svc({
+          ports: [{ startPort: 8080, endPort: 8080, hostIp: '127.0.0.1', protocol: 'tcp' }],
+        }),
+      ],
+    });
+    const r = deriveStackExposure(m, 'test', NOW);
+    expect(r.services[0].publiclyExposed).toBe(false);
+  });
+
+  it('marks ::1 (IPv6 loopback) as not exposed', () => {
+    const m = model({
+      services: [
+        svc({
+          ports: [{ startPort: 8080, endPort: 8080, hostIp: '::1', protocol: 'tcp' }],
+        }),
+      ],
+    });
+    const r = deriveStackExposure(m, 'test', NOW);
+    expect(r.services[0].publiclyExposed).toBe(false);
+  });
+
+  it('marks any 127.0.0.0/8 address as loopback (not exposed)', () => {
+    const m = model({
+      services: [
+        svc({
+          ports: [{ startPort: 8080, endPort: 8080, hostIp: '127.0.0.2', protocol: 'tcp' }],
+        }),
+      ],
+    });
+    const r = deriveStackExposure(m, 'test', NOW);
+    expect(r.services[0].publiclyExposed).toBe(false);
+  });
+
+  it('marks a host-network service as exposed even with no published ports', () => {
+    const m = model({
+      services: [
+        svc({ networkMode: 'host' }),
+      ],
+    });
+    const r = deriveStackExposure(m, 'test', NOW);
+    expect(r.services[0].publiclyExposed).toBe(true);
+    expect(r.services[0].reason).toBe('host-network');
+    expect(r.services[0].bindings).toEqual([]);
+  });
+
+  it('does not mark network_mode: none as exposed', () => {
+    const m = model({
+      services: [
+        svc({ networkMode: 'none' }),
+      ],
+    });
+    const r = deriveStackExposure(m, 'test', NOW);
+    expect(r.services[0].publiclyExposed).toBe(false);
+  });
+
+  it('carries the image reference through for downstream joins', () => {
+    const m = model({
+      services: [
+        svc({
+          image: 'postgres:15',
+          ports: [{ startPort: 5432, endPort: 5432, hostIp: '0.0.0.0', protocol: 'tcp' }],
+        }),
+      ],
+    });
+    const r = deriveStackExposure(m, 'test', NOW);
+    expect(r.services[0].image).toBe('postgres:15');
+  });
+
+  it('sets image to null for build-only services', () => {
+    const m = model({
+      services: [
+        svc({
+          image: undefined,
+          ports: [{ startPort: 3000, endPort: 3000, hostIp: '0.0.0.0', protocol: 'tcp' }],
+        }),
+      ],
+    });
+    const r = deriveStackExposure(m, 'test', NOW);
+    expect(r.services[0].image).toBeNull();
+    expect(r.services[0].publiclyExposed).toBe(true); // still exposed via port
+  });
+
+  it('handles multi-service stacks with mixed exposure', () => {
+    const m = model({
+      services: [
+        svc({
+          name: 'frontend',
+          ports: [{ startPort: 80, endPort: 80, hostIp: '0.0.0.0', protocol: 'tcp' }],
+        }),
+        svc({ name: 'backend', ports: [{ startPort: 4000, endPort: 4000, hostIp: '127.0.0.1', protocol: 'tcp' }] }),
+        svc({ name: 'metrics', networkMode: 'host' }),
+      ],
+    });
+    const r = deriveStackExposure(m, 'test', NOW);
+    expect(r.services[0].publiclyExposed).toBe(true); // frontend
+    expect(r.services[1].publiclyExposed).toBe(false); // backend (loopback)
+    expect(r.services[2].publiclyExposed).toBe(true); // metrics (host network)
+  });
+
+  it('includes the stack name and timestamp in the descriptor', () => {
+    const m = model({ services: [svc({})] });
+    const r = deriveStackExposure(m, 'mystack', NOW);
+    expect(r.stack).toBe('mystack');
+    expect(r.computedAt).toBe(NOW);
+  });
+
+  it('produces bindings in host-only format without container target ports', () => {
+    const m = model({
+      services: [
+        svc({
+          ports: [
+            { startPort: 8080, endPort: 8080, hostIp: '0.0.0.0', protocol: 'tcp' },
+            { startPort: 9000, endPort: 9001, hostIp: '', protocol: 'udp' },
+          ],
+        }),
+      ],
+    });
+    const r = deriveStackExposure(m, 'test', NOW);
+    expect(r.services[0].bindings).toEqual([
+      '0.0.0.0:8080/tcp',
+      '0.0.0.0:9000-9001/udp',
+    ]);
+  });
+});
+
+describe('buildExposedImageMap', () => {
+  function exp(stack: string, services: Array<{ image: string | null; publiclyExposed: boolean }>): StackExposure {
+    return {
+      stack,
+      computedAt: NOW,
+      services: services.map((s) => ({
+        service: 's',
+        image: s.image,
+        publiclyExposed: s.publiclyExposed,
+        reason: s.publiclyExposed ? 'published-port' : null,
+        bindings: [],
+      })),
+    };
+  }
+
+  it('returns an empty map for no exposures', () => {
+    expect(buildExposedImageMap([]).size).toBe(0);
+  });
+
+  it('maps an exposed image to true', () => {
+    const map = buildExposedImageMap([
+      exp('a', [{ image: 'nginx:latest', publiclyExposed: true }]),
+    ]);
+    expect(map.get('nginx:latest')).toBe(true);
+  });
+
+  it('maps an internal-only image to false', () => {
+    const map = buildExposedImageMap([
+      exp('a', [{ image: 'nginx:latest', publiclyExposed: false }]),
+    ]);
+    expect(map.get('nginx:latest')).toBe(false);
+  });
+
+  it('skips build-only services (no image)', () => {
+    const map = buildExposedImageMap([
+      exp('a', [{ image: null, publiclyExposed: true }]),
+    ]);
+    expect(map.has(null as unknown as string)).toBe(false);
+    expect(map.size).toBe(0);
+  });
+
+  it('true wins over false when the same image appears in multiple stacks', () => {
+    const map = buildExposedImageMap([
+      exp('a', [{ image: 'nginx:latest', publiclyExposed: false }]),
+      exp('b', [{ image: 'nginx:latest', publiclyExposed: true }]),
+    ]);
+    expect(map.get('nginx:latest')).toBe(true);
+  });
+
+  it('true stays true even when a later stack classifies the image internal', () => {
+    const map = buildExposedImageMap([
+      exp('a', [{ image: 'nginx:latest', publiclyExposed: true }]),
+      exp('b', [{ image: 'nginx:latest', publiclyExposed: false }]),
+    ]);
+    expect(map.get('nginx:latest')).toBe(true);
+  });
+
+  it('returns false when the image appears only as internal across all stacks', () => {
+    const map = buildExposedImageMap([
+      exp('a', [{ image: 'postgres:15', publiclyExposed: false }]),
+      exp('b', [{ image: 'postgres:15', publiclyExposed: false }]),
+    ]);
+    expect(map.get('postgres:15')).toBe(false);
+  });
+
+  it('leaves an absent image as undefined (no descriptor contains it)', () => {
+    const map = buildExposedImageMap([
+      exp('a', [{ image: 'redis:7', publiclyExposed: true }]),
+    ]);
+    expect(map.get('nginx:latest')).toBeUndefined();
+  });
+
+  it('handles mixed images in the same stack', () => {
+    const map = buildExposedImageMap([
+      exp('a', [
+        { image: 'frontend:1', publiclyExposed: true },
+        { image: 'backend:1', publiclyExposed: false },
+      ]),
+    ]);
+    expect(map.get('frontend:1')).toBe(true);
+    expect(map.get('backend:1')).toBe(false);
+  });
+});
diff --git a/backend/src/routes/security.ts b/backend/src/routes/security.ts
index 9267e65c..7d6c6d39 100644
--- a/backend/src/routes/security.ts
+++ b/backend/src/routes/security.ts
@@ -15,6 +15,7 @@ import { applyMisconfigAcknowledgements } from '../utils/misconfig-ack-filter';
 import { generateSarif } from '../services/SarifExporter';
 import { generateOpenVex } from '../services/OpenVexExporter';
 import { deriveSecurityPosture, type SecurityPostureFacts, type SecurityPostureState } from '../services/securityPosture';
+import { buildExposedImageMap } from '../services/preflight/exposure';
 import { sanitizeForLog } from '../utils/safeLog';
 import { getErrorMessage } from '../utils/errors';
 import { isDebugEnabled } from '../utils/debug';
@@ -555,11 +556,21 @@ securityRouter.get('/scans/:scanId', authMiddleware, (req: Request, res: Respons
   if (!Number.isFinite(scanId)) {
     res.status(400).json({ error: 'Invalid scan id' }); return;
   }
-  const scan = DatabaseService.getInstance().getVulnerabilityScan(scanId);
+  const db = DatabaseService.getInstance();
+  const scan = db.getVulnerabilityScan(scanId);
   if (!scan || scan.node_id !== req.nodeId) {
     res.status(404).json({ error: 'Scan not found' }); return;
   }
-  res.json(shapeScanForResponse(scan));
+  // Attach the exposure status for the scan sheet badge (tri-state:
+  // true = public, false = internal, absent = no descriptor cached).
+  const exposures = db.getStackExposures(req.nodeId);
+  const exposedMap = buildExposedImageMap(
+    exposures.map((r) => {
+      try { return JSON.parse(r.descriptor); } catch { return null; }
+    }).filter(Boolean),
+  );
+  const publiclyExposed = exposedMap.get(scan.image_ref) ?? null;
+  res.json({ ...shapeScanForResponse(scan), publicly_exposed: publiclyExposed });
 });
 
 securityRouter.get(
@@ -752,8 +763,19 @@ securityRouter.get('/overview', authMiddleware, (req: Request, res: Response): v
       }
     }
 
-    // Compose exposure is joined in a later phase; until then it is honestly zero.
-    const publiclyExposed = 0;
+    // Count distinct images that are publicly exposed AND have at least one
+    // non-suppressed Critical/High finding. The exposure descriptor is cached
+    // at deploy/update time, so this is O(stacks) + O(images), zero subprocess.
+    const exposures = db.getStackExposures(req.nodeId);
+    const exposedMap = buildExposedImageMap(
+      exposures.map((r) => {
+        try { return JSON.parse(r.descriptor); } catch { return null; }
+      }).filter(Boolean),
+    );
+    let publiclyExposed = 0;
+    for (const [imageRef] of critHighByImage) {
+      if (exposedMap.get(imageRef) === true) publiclyExposed += 1;
+    }
 
     const postureFacts: SecurityPostureFacts = {
       scannerAvailable: svc.isTrivyAvailable(),
diff --git a/backend/src/routes/stacks.ts b/backend/src/routes/stacks.ts
index b2a86b7d..ff3cfc7d 100644
--- a/backend/src/routes/stacks.ts
+++ b/backend/src/routes/stacks.ts
@@ -946,6 +946,7 @@ stacksRouter.delete('/:stackName', async (req: Request, res: Response) => {
     DatabaseService.getInstance().deleteStackDossier(req.nodeId, stackName);
     DatabaseService.getInstance().deleteStackDriftFindings(req.nodeId, stackName);
     DatabaseService.getInstance().deleteStackExposureIntents(req.nodeId, stackName);
+    DatabaseService.getInstance().deleteStackExposure(req.nodeId, stackName);
     if (debug) console.debug(`[Stacks:debug] Delete: db OK`, { stackName: sanitizedName });
   } catch (dbErr) {
     console.error('[Stacks] Database cleanup failed for %s; files already removed:', sanitizeForLog(stackName), dbErr);
diff --git a/backend/src/services/BlueprintService.ts b/backend/src/services/BlueprintService.ts
index ac4913c3..5667ff9a 100644
--- a/backend/src/services/BlueprintService.ts
+++ b/backend/src/services/BlueprintService.ts
@@ -473,6 +473,13 @@ export class BlueprintService {
                 if (await this.stackDirExists(node.id, blueprint.name)) {
                     await FileSystemService.getInstance(node.id).deleteStack(blueprint.name);
                 }
+                // Remove the exposure descriptor so a withdrawn blueprint
+                // stack does not leave a stale row that escalates posture.
+                try {
+                    DatabaseService.getInstance().deleteStackExposure(node.id, blueprint.name);
+                } catch (e) {
+                    console.warn(`[BlueprintService] deleteStackExposure failed for "${blueprint.name}" on node ${node.id}: ${BlueprintService.formatError(e)}`);
+                }
             },
         );
         if (!lock.ran) {
diff --git a/backend/src/services/ComposeService.ts b/backend/src/services/ComposeService.ts
index 923a45a6..54a139f7 100644
--- a/backend/src/services/ComposeService.ts
+++ b/backend/src/services/ComposeService.ts
@@ -11,6 +11,8 @@ import { LogFormatter } from './LogFormatter';
 import { NodeRegistry } from './NodeRegistry';
 import { RegistryService } from './RegistryService';
 import { DriftLedgerService } from './DriftLedgerService';
+import { parseEffectiveModel } from './preflight/effectiveModel';
+import { deriveStackExposure } from './preflight/exposure';
 
 import { isDebugEnabled } from '../utils/debug';
 import { getErrorMessage } from '../utils/errors';
@@ -481,6 +483,14 @@ export class ComposeService {
     // instead restores the previous files and throws above, so that recovery path
     // reconciles on its next deploy or scan, not here. Best-effort internally.
     await DriftLedgerService.getInstance().reconcileStack(this.nodeId, stackName);
+    // Refresh the exposure cache so posture reflects the just-deployed model.
+    // Best-effort: a refresh failure logs a warning but never fails the deploy.
+    try {
+      await this.refreshExposureCache(stackName);
+    } catch (err) {
+      console.warn('[ComposeService] Exposure refresh failed after deploy for %s:',
+        sanitizeForLog(stackName), sanitizeForLog(getErrorMessage(err, 'unknown')));
+    }
   }
 
   streamLogs(stackName: string, ws: WebSocket) {
@@ -682,6 +692,12 @@ export class ComposeService {
     // reconcile the ledger against the updated runtime.
     await DriftLedgerService.getInstance().recordBaseline(this.nodeId, stackName);
     await DriftLedgerService.getInstance().reconcileStack(this.nodeId, stackName);
+    try {
+      await this.refreshExposureCache(stackName);
+    } catch (err) {
+      console.warn('[ComposeService] Exposure refresh failed after update for %s:',
+        sanitizeForLog(stackName), sanitizeForLog(getErrorMessage(err, 'unknown')));
+    }
   }
 
   public async downStack(stackName: string): Promise<void> {
@@ -728,6 +744,36 @@ export class ComposeService {
     return images;
   }
 
+  /** Render the effective Compose model and cache the per-stack exposure
+   *  descriptor so the Security posture can join exposed images against
+   *  vulnerability findings without re-rendering config on every poll.
+   *  Best-effort: render or parse failure logs a warning and keeps the
+   *  prior cached descriptor, never failing the deploy. */
+  private async refreshExposureCache(stackName: string): Promise<void> {
+    const result = await this.renderConfig(stackName);
+    if (result.rendered === null) {
+      console.warn('[ComposeService] Exposure cache skipped for %s: model not renderable',
+        sanitizeForLog(stackName));
+      return;
+    }
+    let parsed: unknown;
+    try {
+      parsed = JSON.parse(result.rendered);
+    } catch {
+      console.warn('[ComposeService] Exposure cache skipped for %s: unparseable model JSON',
+        sanitizeForLog(stackName));
+      return;
+    }
+    const model = parseEffectiveModel(parsed, stackName);
+    const descriptor = deriveStackExposure(model, stackName, Date.now());
+    DatabaseService.getInstance().upsertStackExposure(
+      this.nodeId,
+      stackName,
+      JSON.stringify(descriptor),
+      descriptor.computedAt,
+    );
+  }
+
   private captureCompose(args: string[], cwd: string): Promise<string> {
     return new Promise((resolve, reject) => {
       const child = spawn('docker', ['compose', ...args], {
diff --git a/backend/src/services/DatabaseService.ts b/backend/src/services/DatabaseService.ts
index 79ace26a..e893b909 100644
--- a/backend/src/services/DatabaseService.ts
+++ b/backend/src/services/DatabaseService.ts
@@ -111,6 +111,15 @@ export interface PreflightRunRow {
     created_by: string | null;
 }
 
+/** Per-stack per-service Compose exposure descriptor (one row per node+stack). */
+export interface StackExposureRow {
+    node_id: number;
+    stack_name: string;
+    /** JSON StackExposure from preflight/exposure.ts. */
+    descriptor: string;
+    computed_at: number;
+}
+
 /** One post-update health gate observation run. */
 export interface HealthGateRunRow {
     id: string;
@@ -1398,6 +1407,14 @@ export class DatabaseService {
       CREATE INDEX IF NOT EXISTS idx_preflight_findings_run
         ON preflight_findings(run_id);
 
+      CREATE TABLE IF NOT EXISTS stack_exposure (
+        node_id INTEGER NOT NULL DEFAULT 0,
+        stack_name TEXT NOT NULL,
+        descriptor TEXT NOT NULL,
+        computed_at INTEGER NOT NULL,
+        PRIMARY KEY (node_id, stack_name)
+      );
+
       CREATE TABLE IF NOT EXISTS health_gate_runs (
         id TEXT PRIMARY KEY,
         node_id INTEGER NOT NULL,
@@ -2504,6 +2521,42 @@ export class DatabaseService {
         this.db.prepare('DELETE FROM stack_exposure_intent WHERE node_id = ? AND stack_name = ?').run(nodeId, stackName);
     }
 
+    // --- Stack Exposure (Compose reachability descriptor) ---
+
+    /** Store a per-stack exposure descriptor, replacing any prior row. */
+    public upsertStackExposure(nodeId: number, stackName: string, descriptor: string, computedAt: number): void {
+        this.db.prepare(
+            `INSERT INTO stack_exposure (node_id, stack_name, descriptor, computed_at)
+             VALUES (?, ?, ?, ?)
+             ON CONFLICT (node_id, stack_name) DO UPDATE SET
+               descriptor = excluded.descriptor,
+               computed_at = excluded.computed_at`
+        ).run(nodeId, stackName, descriptor, computedAt);
+    }
+
+    /** Return every cached exposure descriptor for a node. Malformed rows are
+     *  skipped (logged) so a single corrupt row cannot fail the overview. */
+    public getStackExposures(nodeId: number): StackExposureRow[] {
+        const rows = this.db.prepare(
+            'SELECT node_id, stack_name, descriptor, computed_at FROM stack_exposure WHERE node_id = ?'
+        ).all(nodeId) as StackExposureRow[];
+        return rows.filter((r) => {
+            try {
+                JSON.parse(r.descriptor);
+                return true;
+            } catch {
+                console.warn('[DatabaseService] Dropping malformed stack_exposure row for node=%d stack=%s',
+                    r.node_id, r.stack_name);
+                return false;
+            }
+        });
+    }
+
+    /** Remove the exposure row for a single stack. */
+    public deleteStackExposure(nodeId: number, stackName: string): void {
+        this.db.prepare('DELETE FROM stack_exposure WHERE node_id = ? AND stack_name = ?').run(nodeId, stackName);
+    }
+
     // --- Compose Doctor / Preflight ---
 
     /** Store a run and its findings, replacing any prior run for this (node, stack). */
@@ -2939,6 +2992,7 @@ export class DatabaseService {
             this.db.prepare('DELETE FROM stack_exposure_intent WHERE node_id = ?').run(id);
             this.db.prepare('DELETE FROM preflight_findings WHERE run_id IN (SELECT id FROM preflight_runs WHERE node_id = ?)').run(id);
             this.db.prepare('DELETE FROM preflight_runs WHERE node_id = ?').run(id);
+            this.db.prepare('DELETE FROM stack_exposure WHERE node_id = ?').run(id);
             this.db.prepare('DELETE FROM health_gate_runs WHERE node_id = ?').run(id);
             this.db.prepare('UPDATE blueprints SET pinned_node_id = NULL WHERE pinned_node_id = ?').run(id);
             this.deleteRoleAssignmentsByResource('node', String(id));
diff --git a/backend/src/services/network/normalize.ts b/backend/src/services/network/normalize.ts
index f1d7a796..b7a1daf6 100644
--- a/backend/src/services/network/normalize.ts
+++ b/backend/src/services/network/normalize.ts
@@ -20,7 +20,7 @@ export function isAllInterfaces(ip: string): boolean {
 }
 
 export function isLoopback(ip: string): boolean {
-  return ip === '127.0.0.1' || ip === '::1' || ip === '[::1]';
+  return ip.startsWith('127.') || ip === '::1' || ip === '[::1]';
 }
 
 /** True for `network_mode: host`, which publishes every container port directly
diff --git a/backend/src/services/preflight/exposure.ts b/backend/src/services/preflight/exposure.ts
new file mode 100644
index 00000000..1a0dbb3b
--- /dev/null
+++ b/backend/src/services/preflight/exposure.ts
@@ -0,0 +1,103 @@
+/**
+ * Per-stack/per-service Compose exposure descriptor. Reuses the existing
+ * effective-model parser and the normalize helpers; does not reimplement
+ * port/bind detection.
+ *
+ * Exposure represents CONFIGURED reachability as declared in the Compose
+ * model, refreshed on deploy/update. It is NOT live topology: down/stop
+ * do not clear the cache, just as vulnerability scan data persists after
+ * containers stop. The descriptor reflects what the compose file declares,
+ * not what is currently running.
+ *
+ * The signal is tri-state per image: true (publicly exposed), false
+ * (internal only in every cached stack containing the image), or absent
+ * (no cached descriptor). It is an escalation input for the Security
+ * posture, never an auto-suppression.
+ */
+import type { EffectiveModel } from './effectiveModel';
+import { isLoopback, isHostNetwork } from '../network/normalize';
+
+export interface ServiceExposure {
+  service: string;
+  /** Join key to vulnerability_scans.image_ref. Absent for build-only services. */
+  image: string | null;
+  publiclyExposed: boolean;
+  reason: 'published-port' | 'host-network' | null;
+  /** Host-side binding strings, e.g. "0.0.0.0:8080/tcp". */
+  bindings: string[];
+}
+
+export interface StackExposure {
+  stack: string;
+  services: ServiceExposure[];
+  computedAt: number;
+}
+
+/** Build a port-range label: "8080" for a single port, "8080-8090" for a range. */
+function portLabel(startPort: number, endPort: number): string {
+  return startPort === endPort ? `${startPort}` : `${startPort}-${endPort}`;
+}
+
+/**
+ * Derive a per-stack exposure descriptor from the rendered effective model.
+ * Pure function with no side effects; callers own caching and persistence.
+ */
+export function deriveStackExposure(
+  model: EffectiveModel,
+  stackName: string,
+  now: number,
+): StackExposure {
+  const services: ServiceExposure[] = model.services.map((svc) => {
+    // Publicly exposed when any published port binds to a non-loopback address,
+    // or when network_mode is host (every container port is published on the host).
+    const nonLoopbackPorts = svc.ports.filter((p) => !isLoopback(p.hostIp));
+    const hostNetwork = isHostNetwork(svc.networkMode);
+
+    const publiclyExposed = nonLoopbackPorts.length > 0 || hostNetwork;
+
+    const bindings = nonLoopbackPorts.map(
+      (p) => `${p.hostIp || '0.0.0.0'}:${portLabel(p.startPort, p.endPort)}/${p.protocol}`,
+    );
+
+    return {
+      service: svc.name,
+      image: svc.image ?? null,
+      publiclyExposed,
+      reason: hostNetwork
+        ? 'host-network'
+        : nonLoopbackPorts.length > 0
+          ? 'published-port'
+          : null,
+      bindings,
+    };
+  });
+
+  return { stack: stackName, services, computedAt: now };
+}
+
+/**
+ * Build a per-node image->exposed tri-state map from all cached stack
+ * descriptors. The map answers:
+ *   true  = at least one service using this image is publicly exposed
+ *   false = every cached descriptor containing this image marks it internal-only
+ *   absent = no cached descriptor contains this image (null)
+ *
+ * When multiple stacks contain the same image, one public exposure wins over
+ * any number of internal-only classifications (conservative escalation).
+ */
+export function buildExposedImageMap(
+  exposures: StackExposure[],
+): Map<string, boolean> {
+  const map = new Map<string, boolean>();
+  for (const exp of exposures) {
+    for (const svc of exp.services) {
+      if (!svc.image) continue; // build-only services have no join key
+      const current = map.get(svc.image);
+      // true wins: once an image is known to be publicly exposed anywhere,
+      // it stays true regardless of other stacks classifying it internal.
+      if (current === true) continue;
+      map.set(svc.image, svc.publiclyExposed);
+    }
+  }
+  return map;
+}
diff --git a/frontend/src/components/VulnerabilityScanSheet.tsx b/frontend/src/components/VulnerabilityScanSheet.tsx
index 142dec44..e01aafc3 100644
--- a/frontend/src/components/VulnerabilityScanSheet.tsx
+++ b/frontend/src/components/VulnerabilityScanSheet.tsx
@@ -528,9 +528,14 @@ export function VulnerabilityScanSheet({
     }
   }, [scan]);
 
-  const meta = scan
-    ? `${scan.total_vulnerabilities} vulns · ${scan.fixable_count} fixable · ${scan.triggered_by}`
-    : (loading ? 'Loading…' : 'No scan');
+  const meta = scan ? (
+    <span className="inline-flex flex-wrap items-center gap-2">
+      {scan.total_vulnerabilities} vulns · {scan.fixable_count} fixable · {scan.triggered_by}
+      {scan.publicly_exposed === true && (
+        <EvidenceTag tone="warn">Published service</EvidenceTag>
+      )}
+    </span>
+  ) : (loading ? 'Loading…' : 'No scan');
 
   const footerContext = scan
     ? `Scanned ${formatTimeAgo(new Date(scan.scanned_at).getTime())}`
diff --git a/frontend/src/types/security.ts b/frontend/src/types/security.ts
index 3e8829ff..cde9f49a 100644
--- a/frontend/src/types/security.ts
+++ b/frontend/src/types/security.ts
@@ -70,6 +70,9 @@ export interface VulnerabilityScan {
   error: string | null;
   stack_context: string | null;
   policy_evaluation?: ScanPolicyEvaluation | null;
+  /** Tri-state Compose exposure for the scan-sheet badge: true = publicly
+   *  exposed, false = internal only, null/absent = no descriptor cached. */
+  publicly_exposed?: boolean | null;
 }
 
 export interface SecretFinding {