Mesa provides a 3D graphics API that is compatible with Open Graphics Library (OpenGL). It also provides hardware-accelerated drivers for many popular graphics chips.
An out-of-bounds access flaw was found in Mesa. If an application using Mesa exposed the Mesa API to untrusted inputs (Mozilla Firefox does this), an attacker could cause the application to crash or, potentially, execute arbitrary code with the privileges of the user running the application. (CVE-2013-1872)
It was found that Mesa did not correctly validate messages from the X server. A malicious X server could cause an application using Mesa to crash or, potentially, execute arbitrary code with the privileges of the user running the application. (CVE-2013-1993)
All users of Mesa are advised to upgrade to these updated packages, which contain backported patches to correct these issues. All running applications linked against Mesa must be restarted for this update to take effect.