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Fencer Vulns
medium 4.9

CVE-2007-3731 json

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-ste…

published 2007-09-17 19 y ago modified 2026-06-16 4 mo ago also EUVD-2007-3715

cvss
4.9
version 2.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 43%
public exploits
0
none known

Summary

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.

Patch / fix

  • kernel RHEL 5 2.6.18-8.1.15.el5
  • kernel-PAE RHEL 5 2.6.18-8.1.15.el5
  • kernel-xen RHEL 5 2.6.18-8.1.15.el5
  • kernel-kdump RHEL 5 2.6.18-8.1.15.el5
  • kernel-debuginfo-common RHEL 5 2.6.18-8.1.15.el5

red hat advisories RHSA-2007:0940

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2007-3731 updated

NULL pointer dereference triggered by ptrace

  • Red Hat Enterprise Linux (v. 5 server) kernel 2.6.18-8.1.15.el5, kernel-PAE 2.6.18-8.1.15.el5, kernel-xen 2.6.18-8.1.15.el5, kernel-kdump 2.6.18-8.1.15.el5, kernel-debuginfo-common 2.6.18-8.1.15.el5 Red Hat Enterprise Linux Desktop (v. 5 client) kernel 2.6.18-8.1.15.el5, kernel-PAE 2.6.18-8.1.15.el5, kernel-xen 2.6.18-8.1.15.el5, kernel-kdump 2.6.18-8.1.15.el5, kernel-debuginfo-common 2.6.18-8.1.15.el5
    fixed: vendor fix RHSA-2007:0940

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.51% chance of exploitation in the next 30 days, higher than 43% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • bugzilla.kernel.org http://bugzilla.kernel.org/show_bug.cgi?id=8765 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 2.0 4.9 AV:L/AC:L/Au:N/C:N/I:N/A:C

Classification

Weakness
  • CWE-20 Improper Input Validation
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.