X.Org Server 1.17.1 Released To Fix Yet Another X Security Vulnerability
It's just been one week since the release of X.Org Server 1.17, but the v1.17.1 point release had to come today due to an outstanding XKB security issue.
The vulnerability addressed by xorg-server 1.17.1 is CVE-2015-0255, which was made public today. The newest X.Org CVE is described as:
Olivier Fourdan from Red Hat has discovered a protocol handling issue in the way the X server code base handles the XkbSetGeometry request.News of another security vulnerability isn't a huge surprise as the X11 Server has been home to many security issues dating back many years and there's many issues to find.
The issue stems from the server trusting the client to send valid string lengths in the request data. A malicious client with string lengths exceeding the request length can cause the server to copy adjacent memory data into the XKB structs. This data is then available to the client via the XkbGetGeometry request. The data length is at least up to 64k, it is possible to obtain more data by chaining strings, each string length is then determined by whatever happens to be in that 16-bit region of memory.
A similarly crafted request can likely cause the X server to crash.
This issue has been assigned CVE-2015-0255