It's possible to get access and read configuration files by using URLs such as http://localhost:8080/xwiki/webjars/wiki%3Axwiki/..%2F..%2F..%2F..%2F..%2FWEB-INF%2Fxwiki.cfg. The trick here is to encode the / which is decoded when parsing the URL segment, but not re-encoded when assembling the file path.
This has been patched in 17.4.0-rc-1, 16.10.7.
There is no known workaround, other than upgrading XWiki.
If you have any questions or comments about this advisory:
{
"cwe_ids": [
"CWE-23"
],
"github_reviewed": true,
"github_reviewed_at": "2025-09-03T17:42:51Z",
"nvd_published_at": "2025-09-03T21:15:31Z",
"severity": "CRITICAL"
}