It was discovered that libICE before 1.0.9-8 used a weak entropy to generate keys. A local attacker could potentially use this flaw for session hijacking using the information available from the process list.

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.