The pygrub boot loader emulator in Xen, when nul-delimited output format is requested, allows local pygrub-using guest OS administrators to read or delete arbitrary files on the host via NUL bytes in the bootloader configuration file.Referenceshttp://xenbits.xen.org/xsa/xsa198.patchhttp://www.securityfocus.com/bid/94473https://security.gentoo.org/glsa/201612-56http://xenbits.xen.org/xsa/advisory-198.htmlhttp://www.securitytracker.com/id/1037347https://support.citrix.com/article/CTX218775
