Linux kernel before 2.6.18, when running on x86_64 systems, does not properly save or restore EFLAGS during a context switch, which allows local users to cause a denial of service (crash) by causing SYSENTER to set an NT flag, which can trigger a crash on the IRET of the next task.
http://secunia.com/advisories/24098
http://secunia.com/advisories/25691
http://secunia.com/advisories/26620
http://secunia.com/advisories/26994
http://secunia.com/advisories/32485
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A9554
http://www.debian.org/security/2007/dsa-1381
http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.18
http://www.kernel.org/pub/linux/kernel/v2.6/snapshots/patch-2.6.18-git13.log
http://www.mandriva.com/security/advisories?name=MDKSA-2007:171
Published: 2006-12-31
Base Score: 4.9
Vector: CVSS2#AV:L/AC:L/Au:N/C:N/I:N/A:C
Severity: Medium