fix(cspNonce): don't overwrite existing nonce values

Fixes: #16414

packages/vite/src/node/plugins/html.ts

@@ -1189,6 +1189,13 @@ export function injectNonceAttributeTagHook(
               parseRelAttr(attr.value).some((a) => processRelType.has(a)),
           ))
       ) {
+        const alreadyContainsNonce = node.attrs.some(
+          ({ name }) => name === 'nonce',
+        )
+        if (alreadyContainsNonce) {
+          return
+        }
+
         // if the closing of the start tag includes a `/`, the offset should be 2 so the nonce
         // is appended prior to the `/`
         const appendOffset =

playground/csp/__tests__/csp.spec.ts

@@ -27,6 +27,20 @@ test('dynamic js', async () => {
   )
 })
 
+test('inline js', async () => {
+  await expectWithRetry(() => page.textContent('.inline-js')).toBe(
+    'inline-js: ok',
+  )
+})
+
+test('nonce attributes are not repeated', async () => {
+  const htmlSource = await page.content()
+  expect(htmlSource).not.toContain(/nonce=""[^>]*nonce=""/)
+  await expectWithRetry(() => page.textContent('.double-nonce-js')).toBe(
+    'double-nonce-js: ok',
+  )
+})
+
 test('meta[property=csp-nonce] is injected', async () => {
   const meta = await page.$('meta[property=csp-nonce]')
   expect(await (await meta.getProperty('nonce')).jsonValue()).not.toBe('')

playground/csp/index.html

@@ -11,3 +11,13 @@
 <p class="dynamic">dynamic</p>
 <p class="js">js: error</p>
 <p class="dynamic-js">dynamic-js: error</p>
+<p class="inline-js">inline-js: error</p>
+<p class="double-nonce-js">double-nonce-js: error</p>
+<script>
+  document.querySelector('.inline-js').textContent = 'inline-js: ok'
+</script>
+<script nonce="#$NONCE$#">
+  // this test case is to ensure that the nonce isn't being
+  // double-applied if an existing attribute is present.
+  document.querySelector('.double-nonce-js').textContent = 'double-nonce-js: ok'
+</script>