2. Summary of updates in 4.2.1.

2.1. Security

• Fix a zlib bug that may have security implications on some platforms.
• MIT-SHM update to not access SHM segments that the client doesn't have sufficient privileges to access.
• Fix an Xlib problem that made it possible to load (and execute) arbitrary code in privileged clients.

2.2. Other

• Revert the ATI driver's composite sync default to a safer value.
• Fix Xlib's modular i18n support on Solaris.
• Fix an X server crash when printing some types of modes.
• Startx and xon script fixes.
• Fix a colormap bug with 24+8 overlay mode.
• Update XDarwin support for the Jaguar release.
• Xaw bug fix.
• Fix a vesa driver floating point exception.
• Fix Emulate3Buttons for wsmouse protocol on NetBSD and OpenBSD.