Race condition in the setsid function in Linux before 2.6.8.1 allows local users to cause a denial of service (crash) and possibly access portions of kernel memory, related to TTY changes, locking, and semaphores.

Linux VServer 1.27 and earlier, 1.3.9 and earlier, and 1.9.1 and earlier shares /proc permissions across all virtual and host servers, which allows local users with the ability to set permissions in /proc to obtain system information or cause a denial of service on other virtual servers or the host server.