It was discovered that libXdmcp before 1.1.2 including used weak entropy to generate session keys. On a multi-user system using xdmcp, a local attacker could potentially use information available from the process list to brute force the key, allowing them to hijack other users' sessions.
xorg-x11-server before 1.19.5 was missing extra length validation in ProcEstablishConnection function allowing malicious X client to cause X server to crash or possibly execute arbitrary code.
xorg-x11-server before 1.19.5 was vulnerable to integer overflow in ProcDbeGetVisualInfo function allowing malicious X client to cause X server to crash or possibly execute arbitrary code.
xorg-x11-server before 1.19.5 had wrong extra length check in ProcXIChangeHierarchy function allowing malicious X client to cause X server to crash or possibly execute arbitrary code.
xorg-x11-server before 1.19.5 was vulnerable to integer overflow in (S)ProcXIBarrierReleasePointer functions allowing malicious X client to cause X server to crash or possibly execute arbitrary code.
xorg-x11-server before 1.19.5 was missing length validation in XFree86 VidModeExtension allowing malicious X client to cause X server to crash or possibly execute arbitrary code.
xorg-x11-server before 1.19.5 was missing length validation in XFree86 DGA extension allowing malicious X client to cause X server to crash or possibly execute arbitrary code.
xorg-x11-server before 1.19.5 was missing length validation in XFree86 DRI extension allowing malicious X client to cause X server to crash or possibly execute arbitrary code.
xorg-x11-server before 1.19.5 was missing length validation in XFIXES extension allowing malicious X client to cause X server to crash or possibly execute arbitrary code.
xorg-x11-server before 1.19.5 was missing length validation in XINERAMA extension allowing malicious X client to cause X server to crash or possibly execute arbitrary code.