CVE Vulnerabilities


Improper Restriction of XML External Entity Reference

Published: Apr 28, 2022 | Modified: May 10, 2022
CVSS 3.x
CVSS 2.x

org.xwiki.commons:xwiki-commons-xml is a common module used by other XWiki top level projects. Starting in version 2.7 and prior to versions 12.10.10, 13.4.4, and 13.8-rc-1, it is possible for a script to access any file accessing to the user running XWiki application server with XML External Entity Injection through the XML script service. The problem has been patched in versions 12.10.10, 13.4.4, and 13.8-rc-1. There is no easy workaround for fixing this vulnerability other than upgrading and being careful when giving Script rights.


The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.

Affected Software

Name Vendor Start Version End Version
Commons Xwiki 2.7 (including) 12.10.10 (excluding)
Commons Xwiki 13.0 (including) 13.4.4 (excluding)
Commons Xwiki 13.5 (including) 13.8 (excluding)

Extended Description

XML documents optionally contain a Document Type Definition (DTD), which, among other features, enables the definition of XML entities. It is possible to define an entity by providing a substitution string in the form of a URI. The XML parser can access the contents of this URI and embed these contents back into the XML document for further processing. By submitting an XML file that defines an external entity with a file:// URI, an attacker can cause the processing application to read the contents of a local file. For example, a URI such as “file:///c:/winnt/win.ini” designates (in Windows) the file C:\Winnt\win.ini, or file:///etc/passwd designates the password file in Unix-based systems. Using URIs with other schemes such as http://, the attacker can force the application to make outgoing requests to servers that the attacker cannot reach directly, which can be used to bypass firewall restrictions or hide the source of attacks such as port scanning. Once the content of the URI is read, it is fed back into the application that is processing the XML. This application may echo back the data (e.g. in an error message), thereby exposing the file contents.

Potential Mitigations