fix(cspNonce): don't overwrite existing nonce values (#16415)

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

@@ -1180,24 +1180,29 @@ export function injectNonceAttributeTagHook(
         return
       }
 
+      const { nodeName, attrs, sourceCodeLocation } = node
+
       if (
-        node.nodeName === 'script' ||
-        (node.nodeName === 'link' &&
-          node.attrs.some(
+        nodeName === 'script' ||
+        (nodeName === 'link' &&
+          attrs.some(
             (attr) =>
               attr.name === 'rel' &&
               parseRelAttr(attr.value).some((a) => processRelType.has(a)),
           ))
       ) {
+        // If we already have a nonce attribute, we don't need to add another one
+        if (attrs.some(({ name }) => name === 'nonce')) {
+          return
+        }
+
+        const startTagEndOffset = sourceCodeLocation!.startTag!.endOffset
+
         // if the closing of the start tag includes a `/`, the offset should be 2 so the nonce
         // is appended prior to the `/`
-        const appendOffset =
-          html[node.sourceCodeLocation!.startTag!.endOffset - 2] === '/' ? 2 : 1
+        const appendOffset = html[startTagEndOffset - 2] === '/' ? 2 : 1
 
-        s.appendRight(
-          node.sourceCodeLocation!.startTag!.endOffset - appendOffset,
-          ` nonce="${nonce}"`,
-        )
+        s.appendRight(startTagEndOffset - appendOffset, ` nonce="${nonce}"`)
       }
     })
 

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>