CVE-2007-3731: Linux Kernel

Medium severity, CVSS 4.9. EPSS: 0.5% chance of exploitation in the next 30 days.

The Linux kernel 2.6.20 and 2.6.21 does not properly handle an invalid LDT segment selector in %cs (the xcs field) during ptrace single-step operations, which allows local users to cause a denial of service (NULL dereference and OOPS) via certain code that makes ptrace PTRACE_SETREGS and PTRACE_SINGLESTEP requests, related to the TRACE_IRQS_ON function, and possibly related to the arch_ptrace function.

Affected products

• Linux Linux Kernel: version 2.6.20 only; version 2.6.21 only

Published 2007-09-17. Last modified 2026-06-16.