Vulnerability Note VU#176888

Linux kernel contains race condition via ptrace/procfs/execve

Original Release date: 18 Jul 2001 | Last revised: 20 May 2002


Unprivileged local users can use the ptrace function to take advantage of a privileged program, while that program is performing a privileged operation, to gain privileged access.


Ptrace is a function, which is often used for debugging, that allows one process to attach to another and monitor or modify its execution state and memory. This vulnerability exploits a race condition that allows an attacker to use ptrace, or similar function (procfs), to attach to and, thus, modify a running setuid process. This enables the attacker to execute arbitratry code with elevated (root) privilege. Linux kernel version 2.2.18 or before are vulnerable to this flaw. Any Linux product that is dependent on this kernel is, therefore, vulnerable.


Unprivileged local users can gain privileged (root) access.


Upgrade the Linux kernel to version 2.2.19 or later. The release notes for Linux 2.2.19 at describe the security fix. For users of specific Linux vendors, use the vendor-specific upgrades for convenience and consistency.

Systems Affected (Learn More)

VendorStatusDate NotifiedDate Updated
CalderaAffected03 Apr 200120 May 2002
ConectivaAffected19 Apr 200120 May 2002
DebianAffected16 Apr 200120 May 2002
ImmunixAffected26 Mar 200120 May 2002
MandrakeSoftAffected17 Apr 200120 May 2002
NetBSDAffected15 Jun 200120 May 2002
Progency Linux SystemsAffected10 Apr 200120 May 2002
Red HatAffected10 Apr 200120 May 2002
SuSEAffected17 May 200120 May 2002
TrustixAffected05 Apr 200120 May 2002
SlackwareUnknown-20 May 2002
If you are a vendor and your product is affected, let us know.

CVSS Metrics (Learn More)

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A N/A



Thanks to Wojciech Purczynski for discovering this vulnerability.

This document was written by Andrew P. Moore.

Other Information

  • CVE IDs: CVE-2001-0317
  • Date Public: 26 Mar 2001
  • Date First Published: 18 Jul 2001
  • Date Last Updated: 20 May 2002
  • Severity Metric: 25.99
  • Document Revision: 29


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