diff --git a/scripts/validate-metrics.mjs b/scripts/validate-metrics.mjs
index bb06eca0..bb248fe5 100644
--- a/scripts/validate-metrics.mjs
+++ b/scripts/validate-metrics.mjs
@@ -3,25 +3,52 @@ import { readFileSync } from 'node:fs';
 import { reportAndExit } from './lib/validate-utils.mjs';
 const data = JSON.parse(readFileSync(new URL('../data/metrics.json', import.meta.url)));
 const errors = [];
+
+// Every URL in metrics.json is rendered straight into an <a href> by
+// src/components/MetricsDashboard and src/components/ReferenceArchitectures,
+// so an href-bearing scheme other than https reaching the published site is an
+// active-content sink. Absent values are left to the existing presence checks.
+function checkUrl(path, field, value) {
+  if (value === undefined || value === null || value === '') return;
+  let parsed;
+  try {
+    parsed = new URL(value);
+  } catch {
+    errors.push({ path, severity: 'error', message: `${field} must be an absolute URL` });
+    return;
+  }
+  if (parsed.protocol !== 'https:') errors.push({ path, severity: 'error', message: `${field} must use https, got ${parsed.protocol}` });
+}
+
 if (!data.generated) errors.push({ path: 'metrics.json', severity: 'error', message: 'generated must be true' });
 if (Number.isNaN(Date.parse(data.generatedAt))) errors.push({ path: 'metrics.json', severity: 'error', message: 'generatedAt must be ISO 8601' });
 if (!data.sources?.landscape?.revision || !data.sources?.architectures?.revision) errors.push({ path: 'metrics.json', severity: 'error', message: 'source revisions are required' });
+for (const name of ['landscape', 'architectures']) {
+  const source = data.sources?.[name];
+  if (!source) continue;
+  checkUrl(`sources.${name}`, 'repository', source.repository);
+  checkUrl(`sources.${name}`, 'sourceUrl', source.sourceUrl);
+}
+checkUrl('referenceArchitectureLifecycle', 'sourceUrl', data.referenceArchitectureLifecycle?.sourceUrl);
 const ids = new Set();
 for (const metric of data.metrics || []) {
   if (!metric.id || ids.has(metric.id)) errors.push({ path: metric.id, severity: 'error', message: 'duplicate or missing metric id' });
   ids.add(metric.id);
   if (metric.value === undefined || metric.value === null || metric.value === '') errors.push({ path: metric.id, severity: 'error', message: 'missing value' });
   if (!metric.source || !metric.sourceUrl || !metric.collectedAt) errors.push({ path: metric.id, severity: 'error', message: 'missing provenance' });
+  checkUrl(metric.id, 'sourceUrl', metric.sourceUrl);
 }
 for (const item of data.omitted || []) if (!item.id || !item.reason) errors.push({ path: 'metrics.json', severity: 'error', message: 'omitted metrics require id and reason' });
 for (const card of data.referenceArchitectureLifecycle?.cards || []) if (!card.id || !card.label || !Number.isFinite(card.value)) errors.push({ path: 'metrics.json', severity: 'error', message: 'invalid lifecycle card' });
 for (const item of data.referenceArchitectureLifecycle?.omitted || []) if (!item.id || !item.reason) errors.push({ path: 'metrics.json', severity: 'error', message: 'invalid lifecycle omission' });
-for (const series of Object.values(data.series || {})) {
+for (const [id, series] of Object.entries(data.series || {})) {
   if (!series.label || !series.sourceUrl || !Array.isArray(series.values) || !series.values.length) errors.push({ path: 'metrics.json', severity: 'error', message: 'invalid time series' });
+  checkUrl(`series.${id}`, 'sourceUrl', series.sourceUrl);
   for (const point of series.values || []) if (!point.date || !Number.isFinite(point.value)) errors.push({ path: 'metrics.json', severity: 'error', message: 'invalid time-series point' });
 }
-for (const chart of Object.values(data.breakdowns || {})) {
+for (const [id, chart] of Object.entries(data.breakdowns || {})) {
   if (!chart.label || !chart.sourceUrl || !Array.isArray(chart.values)) errors.push({ path: 'metrics.json', severity: 'error', message: 'invalid breakdown' });
+  checkUrl(`breakdowns.${id}`, 'sourceUrl', chart.sourceUrl);
   for (const item of chart.values || []) if (!item.name || !Number.isFinite(item.value)) errors.push({ path: 'metrics.json', severity: 'error', message: 'invalid breakdown value' });
 }
 reportAndExit(errors, 'metrics');
diff --git a/tests/validate-metrics-urls.test.mjs b/tests/validate-metrics-urls.test.mjs
new file mode 100644
index 00000000..8ee20a8d
--- /dev/null
+++ b/tests/validate-metrics-urls.test.mjs
@@ -0,0 +1,144 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { runScriptWithFixtures } from './helpers.mjs';
+
+const SCRIPT = 'validate-metrics.mjs';
+
+const validMetric = {
+  id: 'cncf-projects',
+  label: 'CNCF projects',
+  value: 100,
+  source: 'landscape',
+  sourceUrl: 'https://landscape.cncf.io/',
+  collectedAt: '2026-08-07T00:00:00.000Z',
+};
+
+const validData = {
+  generated: true,
+  generatedAt: '2026-08-07T00:00:00.000Z',
+  sources: {
+    landscape: {
+      repository: 'https://github.com/cncf/landscape',
+      revision: 'abc123',
+      sourceUrl: 'https://github.com/cncf/landscape/blob/main/landscape.yml',
+    },
+    architectures: {
+      repository: 'https://github.com/cncf/architecture',
+      revision: 'def456',
+      sourceUrl:
+        'https://github.com/cncf/architecture/tree/main/content/en/architectures',
+    },
+  },
+  metrics: [validMetric],
+  referenceArchitectureLifecycle: {
+    sourceUrl: 'https://github.com/cncf/tab/issues',
+    cards: [],
+    omitted: [],
+  },
+  series: {
+    endUserMembers: {
+      label: 'CNCF member companies',
+      source: 'landscape',
+      sourceUrl: 'https://landscape.cncf.io/',
+      values: [{ date: '2026-01-01', value: 1 }],
+    },
+  },
+  breakdowns: {
+    projectMaturity: {
+      label: 'Project maturity',
+      source: 'landscape',
+      sourceUrl: 'https://landscape.cncf.io/',
+      values: [{ name: 'graduated', value: 1 }],
+    },
+  },
+};
+
+function fixture(data) {
+  return { 'data/metrics.json': JSON.stringify(data) };
+}
+
+function clone(data) {
+  return JSON.parse(JSON.stringify(data));
+}
+
+test('accepts a metrics file whose URLs are all https', () => {
+  const result = runScriptWithFixtures(SCRIPT, fixture(validData));
+  assert.equal(result.status, 0, result.stderr);
+});
+
+test('rejects a javascript: metric sourceUrl', () => {
+  const data = clone(validData);
+  data.metrics[0].sourceUrl = 'javascript:alert(document.domain)';
+  const result = runScriptWithFixtures(SCRIPT, fixture(data));
+  assert.equal(result.status, 1);
+  assert.match(result.stderr, /sourceUrl must use https, got javascript:/);
+});
+
+test('rejects a data: series sourceUrl', () => {
+  const data = clone(validData);
+  data.series.endUserMembers.sourceUrl = 'data:text/html,<script></script>';
+  const result = runScriptWithFixtures(SCRIPT, fixture(data));
+  assert.equal(result.status, 1);
+  assert.match(
+    result.stderr,
+    /series\.endUserMembers: sourceUrl must use https/,
+  );
+});
+
+test('rejects a javascript: breakdown sourceUrl', () => {
+  const data = clone(validData);
+  data.breakdowns.projectMaturity.sourceUrl = 'javascript:alert(1)';
+  const result = runScriptWithFixtures(SCRIPT, fixture(data));
+  assert.equal(result.status, 1);
+  assert.match(
+    result.stderr,
+    /breakdowns\.projectMaturity: sourceUrl must use https/,
+  );
+});
+
+test('rejects a javascript: lifecycle sourceUrl', () => {
+  const data = clone(validData);
+  data.referenceArchitectureLifecycle.sourceUrl = 'javascript:alert(1)';
+  const result = runScriptWithFixtures(SCRIPT, fixture(data));
+  assert.equal(result.status, 1);
+  assert.match(
+    result.stderr,
+    /referenceArchitectureLifecycle: sourceUrl must use https/,
+  );
+});
+
+test('rejects a javascript: source repository, which is concatenated into a commit href', () => {
+  const data = clone(validData);
+  data.sources.architectures.repository = 'javascript:alert(1)';
+  const result = runScriptWithFixtures(SCRIPT, fixture(data));
+  assert.equal(result.status, 1);
+  assert.match(
+    result.stderr,
+    /sources\.architectures: repository must use https/,
+  );
+});
+
+test('rejects an http: source sourceUrl', () => {
+  const data = clone(validData);
+  data.sources.landscape.sourceUrl = 'http://landscape.cncf.io/';
+  const result = runScriptWithFixtures(SCRIPT, fixture(data));
+  assert.equal(result.status, 1);
+  assert.match(result.stderr, /sources\.landscape: sourceUrl must use https/);
+});
+
+test('rejects a relative metric sourceUrl', () => {
+  const data = clone(validData);
+  data.metrics[0].sourceUrl = '/img/architectures/x.svg';
+  const result = runScriptWithFixtures(SCRIPT, fixture(data));
+  assert.equal(result.status, 1);
+  assert.match(result.stderr, /sourceUrl must be an absolute URL/);
+});
+
+test('leaves absent optional URLs to the existing presence checks', () => {
+  const data = clone(validData);
+  delete data.sources.landscape.repository;
+  delete data.sources.landscape.sourceUrl;
+  delete data.referenceArchitectureLifecycle.sourceUrl;
+  const result = runScriptWithFixtures(SCRIPT, fixture(data));
+  assert.equal(result.status, 0, result.stderr);
+});