[Low] GHSA-x6g4-fwcc-jj8w Symfony has XXE (Local File Disclosure) in DomCrawler::addXmlContent() via validateOnParse = true

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

Published May 27, 2026 CVSS 0.0

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 for branch 5.4.

Credits

Symfony would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.

Affected AI Products

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