Mono provides the necessary software to develop and run .NET client and server applications on various platforms.
Jose Ramon Palanco has discovered that the System.Web class in the XSP for the ASP.NET server 1.1 through 2.0 in Mono does not properly validate or sanitize local pathnames which could allow server-side file content disclosure.
An attacker could append a space character to a URI and obtain unauthorized access to the source code of server-side files. An attacker could also read credentials by requesting Web.Config%20 from a Mono server.
There is no known workaround at this time.
All Mono users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=dev-lang/mono-1.2.2.1"