Merge pull request from GHSA-xjcj-p2qv-q3rf

Et43 · NGPixel · web-flow · commit 1238d614e159 · 2024-05-13T14:57:17.000-04:00
* Update render.js

# Improved handling of mustache expressions and v-pre attribute assignment

## Changes Made:
- Ensured that the parent tag of such text nodes is explicitly set to a `&lt;p&gt;` tag with the `v-pre` attribute.
- Added debug messages for better understanding of the script execution flow [THIS SHOULD REMOVED WHEN PUSHING TO PRODUCTION].

## Why it Works:
- When a mustache expression is found, the script either wraps it in a new `&lt;p&gt;` tag with the `v-pre` attribute or adds the `v-pre` attribute to the existing parent `&lt;p&gt;` tag.
- This approach ensures that the template code is not removed but encapsulated within `&lt;p&gt;` tags with the `v-pre` attribute, as required.

## Test Cases Passed:
1. `&lt;xyz&gt;{{ constructor.constructor('alert(1)')() }}&lt;/xyz&gt;`
2. `&lt;xyz&gt;{{ constructor.constructor('alert(1)')() }}&lt;/xyz&gt;`
3. `&lt;p&gt;&lt;xyz&gt;{{ constructor.constructor('alert(1)')() }}&lt;/p&gt;`
4. `&lt;p&gt;&lt;xyz&gt;{{ constructor.constructor('alert(1)')() }}&lt;/xyz&gt;&lt;/p&gt;`
5. `&lt;p&gt;&amp;lt;xyz&amp;gt;{{constructor.constructor('alert("Test Case 8")')()}}&amp;lt;xyz&amp;gt;{{constructor.constructor('alert("Test Case 9")')()}}&amp;lt;/xyz&amp;gt;&lt;/p&gt;`

This commit enhances the robustness and reliability of handling mustache expressions and ensures proper assignment of the `v-pre` attribute, to ensure that there is no room for the weaponization of the template code later in the rendering process.

* fix: move template expressions after dom-purify + handle text nodes without parent

---------

Co-authored-by: NGPixel &lt;github@ngpixel.com&gt;
diff --git a/server/modules/rendering/html-core/renderer.js b/server/modules/rendering/html-core/renderer.js
@@ -10,7 +10,7 @@ const mustacheRegExp = /(\{|&#x7b;?){2}(.+?)(\}|&#x7d;?){2}/i
 
 module.exports = {
   async render() {
-    const $ = cheerio.load(this.input, {
+    let $ = cheerio.load(this.input, {
       decodeEntities: true
     })
 
@@ -253,17 +253,35 @@ module.exports = {
       }
     })
 
+    // --------------------------------
+    // STEP: POST
+    // --------------------------------
+
+    let output = decodeEscape($.html('body').replace('<body>', '').replace('</body>', ''))
+
+    for (let child of _.sortBy(_.filter(this.children, ['step', 'post']), ['order'])) {
+      const renderer = require(`../${_.kebabCase(child.key)}/renderer.js`)
+      output = await renderer.init(output, child.config)
+    }
+
     // --------------------------------
     // Escape mustache expresions
     // --------------------------------
 
+    $ = cheerio.load(output, {
+      decodeEntities: true
+    })
+
     function iterateMustacheNode (node) {
-      const list = $(node).contents().toArray()
-      list.forEach(item => {
+      $(node).contents().each((idx, item) => {
         if (item && item.type === 'text') {
           const rawText = $(item).text().replace(/\r?\n|\r/g, '')
           if (mustacheRegExp.test(rawText)) {
-            $(item).parent().attr('v-pre', true)
+            if (!item.parent || item.parent.name === 'body') {
+              $(item).wrap($('<p>').attr('v-pre', true))
+            } else {
+              $(item).parent().attr('v-pre', true)
+            }
           }
         } else {
           iterateMustacheNode(item)
@@ -276,18 +294,7 @@ module.exports = {
       $(elm).attr('v-pre', true)
     })
 
-    // --------------------------------
-    // STEP: POST
-    // --------------------------------
-
-    let output = decodeEscape($.html('body').replace('<body>', '').replace('</body>', ''))
-
-    for (let child of _.sortBy(_.filter(this.children, ['step', 'post']), ['order'])) {
-      const renderer = require(`../${_.kebabCase(child.key)}/renderer.js`)
-      output = await renderer.init(output, child.config)
-    }
-
-    return output
+    return decodeEscape($.html('body').replace('<body>', '').replace('</body>', ''))
   }
 }
 
