Symfony has XXE (Local File Disclosure) in DomCrawler::addXmlContent() via validateOnParse = true
Date: 2026-05
Affected: composer/symfony/symfony, composer/symfony/symfony, composer/symfony/symfony
Attack vector: other
Category: vulnerability-disclosure
Severity: Low
CVE: CVE-2026-45071
CWE: CWE-611

### 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.


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Architectural layers (MAESTRO):