GHSA-x6g4-fwcc-jj8w

Symfony has XXE (Local File Disclosure) in DomCrawler::addXmlContent() via validateOnParse = true

### Description `symfony/dom-crawler` provides the `Crawler` class for navigating HTML/XML documents with CSS/XPath selectors; `symfony/browser-kit`'s `HttpBrowser` uses it to parse fetched pages. `Crawler::addXmlContent()` sets `DOMDocument::$validateOnParse = true` before calling `loadXML()`. Setting `validateOnParse` re-enables libxml's DTD subset processing, including external entity resolution, even though `LIBXML_NONET` is passed. `LIBXML_NONET` blocks **network** fetches but not `file://` entities. An attacker-supplied XML document with a `SYSTEM "file:///etc/passwd"` entity is therefore expanded. ### Resolution The `Crawler::addXmlContent` method does not set the `validateOnParse` flag anymore. The patch for this issue is available [here](https://github.com/symfony/symfony/commit/eea5fd7488cbdc241da4ce242344b7d9a3ecdf3d) for branch 5.4. ### Credits Symfony would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.