OWSLib is a Python package for client programming with Open Geospatial Consortium (OGC) web service interface standards, and their related content models. OWSLibs XML parser (which supports both lxml and xml.etree) does not disable entity resolution, and could lead to arbitrary file reads from an attacker-controlled XML payload. This affects all XML parsing in the codebase. This issue has been addressed in version 0.28.1. All users are advised to upgrade. The only known workaround is to patch the library manually. See GHSA-8h9c-r582-mggc for details.
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.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Owslib | Osgeo | * | 0.28.1 (excluding) |
| Owslib | Ubuntu | bionic | * |
| Owslib | Ubuntu | kinetic | * |
| Owslib | Ubuntu | lunar | * |
| Owslib | Ubuntu | mantic | * |
| Owslib | Ubuntu | trusty | * |
| Owslib | Ubuntu | xenial | * |
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.