Debian glibc 2 symlink issue could allow arbitrary file overwriting

ID VU:664141
Type cert
Reporter CERT
Modified 2001-07-31T16:29:00



Some versions of, the loader for shared libraries in UNIX/LINUX, do not properly clear risky environment variables, allowing a symlink attack to overwrite arbitrary files.


LD_DEBUG_OUTPUT specifies a directory in which creates a file with a predictable name based on the process ID. uses this file to store debugging information. The current version of does not unset the environment variable LD_DEBUG_OUTPUT prior to calling setuid root programs. Even though setuid root programs are forced to ignore the LD_DEBUG_OUTPUT variable, output would be generated there by programs called from setuid root programs.


By setting up appropriate symlinks, a malicious user could cause arbitrary files to be overwritten with debugging information.


Pending patch information by the vendor, CERT/CC is unaware of a practical solution to this problem.

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Debian Affected

Notified: May 25, 2001 Updated: June 08, 2001



Vendor Statement

We have not received a statement from the vendor.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.


The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

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The original report of this vulnerabilty was by Jakub Vlasek .

This document was last modifed by Tim Shimeall.

Other Information

CVE IDs: | CVE-2000-0959
Severity Metric: | 0.11
Date Public: | 2000-09-26
Date First Published: | 2001-07-24
Date Last Updated: | 2001-07-31 16:29 UTC
Document Revision: | 8