CVE-2007-3731

What it is

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.

At a glance

Exploitability

Can be exploited locally on the machine without logging in. High risk of service disruption.

Exploit odds

0.5% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2007-09-17 17:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-16 22:42 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.5% in the next 30 days (EPSS).
• Severity: 4.9 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2007-09-17 17:17 UTC

Last modified

2026-06-16 22:42 UTC

Exploit probability

0.5% · EPSS, next 30 days

Weakness

CWE-20 · Improper input validation

Record status

Modified

Affected

• Linux Kernel 2.6.20
• Linux Kernel 2.6.21

Attack profile CVSS 2.0 · 4.9

Attack vector

Local

Complexity

Low

Authentication

None

Confidentiality

None

Integrity

None

Availability

Complete

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2007-3731.md and follow it. Check whether this project is affected by CVE-2007-3731. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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