The XListFonts function in X.org libX11 before 1.6.4 might allow remote X servers to gain privileges via vectors involving length fields, which trigger out-of-bounds write operations.
The XGetImage function in X.org libX11 before 1.6.4 might allow remote X servers to gain privileges via vectors involving image type and geometry, which triggers out-of-bounds read operations.
Multiple off-by-one errors in the (1) MakeBigReq and (2) SetReqLen macros in include/X11/Xlibint.h in X11R6.x and libX11 before 1.6.0 allow remote attackers to have unspecified impact via a crafted request, which triggers a buffer overflow.
Multiple integer overflows in (1) the XGetPixel function in ImUtil.c in X.Org libx11 before 1.0.3, and (2) XInitImage function in xwd.c for ImageMagick, allow user-assisted remote attackers to cause a denial of service (crash) or obtain sensitive information via crafted images with large or negative values that trigger a buffer overflow.
The Xinput module (modules/im/ximcp/imLcIm.c) in X.Org libX11 1.0.2 and 1.0.3 opens a file for reading twice using the same file descriptor, which causes a file descriptor leak that allows local users to read files specified by the XCOMPOSEFILE environment variable via the duplicate file descriptor.