CVE-2026-17615

A flaw was found in RESTEasy's SourceProvider. This vulnerability allows an unauthenticated attacker to perform an unauthenticated remote file read. By sending a specially crafted XML body with a DOCTYPE declaration referencing external entities to an endpoint that accepts application/xml and returns Source or StreamSource, the server can be tricked into resolving the entity and including sensitive file contents in the HTTP response. This is due to the SourceProvider.writeTo() method creating a SAXParser without disabling external entity resolution, leading to an XML External Entity (XXE) vulnerability.

Important: This flaw allows unauthenticated remote file disclosure due to improper XML external entity (XXE) resolution in RESTEasy's SourceProvider. An attacker can exploit this by sending a crafted XML request to an exposed endpoint that processes application/xml and returns Source or StreamSource types, leading to the disclosure of sensitive server-side files. This affects applications utilizing RESTEasy where endpoints are configured to accept XML input and return Source or StreamSource objects, potentially exposing sensitive data on Red Hat supported products.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this issue, avoid exposing RESTEasy endpoints that return Source or StreamSource types. Alternatively, implement a custom MessageBodyWriter for Source types that explicitly applies XML security features to the SAXParserFactory before parsing. Changes to application configuration or code typically require an application redeployment or restart to take effect.