Mandrake alert: Updated gdm packages fix vulnerabilities
Several vulnerabilities were discovered in versions of gdm prior to 18.104.22.168. The first vulnerability is that any user can read any text file on the system due to code originally written to be run as the user logging in was in fact being run as the root user. This code is what allows the examination of the ~/.xsession-errors file. If a user makes a symlink from this file to any other file on the system during the session and ensures that the session lasts less than ten seconds, the user can read the file provided it was readable as a text file.
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Mandrake Linux Security Update Advisory
Package name: gdm
Advisory ID: MDKSA-2003:085
Date: August 21st, 2003
Affected versions: 9.0, 9.1, Corporate Server 2.1
Several vulnerabilities were discovered in versions of gdm prior to
22.214.171.124. The first vulnerability is that any user can read any text
file on the system due to code originally written to be run as the user
logging in was in fact being run as the root user. This code is what
allows the examination of the ~/.xsession-errors file. If a user makes
a symlink from this file to any other file on the system during the
session and ensures that the session lasts less than ten seconds, the
user can read the file provided it was readable as a text file.
Another two vulnerabilities were found in the XDMCP code that could be
exploited to crash the main gdm daemon which would inhibit starting
any new sessions (although the current session would be unaffected).
The first problem here is due to the indirect query structure being
used right after being freed due to a missing 'continue' statement in a
loop; this happens if a choice of server expired and the client tried
The second XDMCP problem is that when authorization data is being
checked as a string, the length is not checked first. If the data is
less than 18 bytes long, the daemon may wander off the end of the
string a few bytes in the strncmp which could cause a SEGV.
These updated packages bring gdm to version 126.96.36.199 which is not
vulnerable to any of these problems. Also note that XDMCP support is
disabled by default in gdm.
Corporate Server 2.1:
Corporate Server 2.1/x86_64:
Mandrake Linux 9.0:
Mandrake Linux 9.1:
Mandrake Linux 9.1/PPC:
Bug IDs fixed (see https://qa.mandrakesoft.com for more information):
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gpg --recv-keys --keyserver http://www.mandrakesecure.net 0x22458A98
Please be aware that sometimes it takes the mirrors a few hours to
You can view other update advisories for Mandrake Linux at:
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If you want to report vulnerabilities, please contact
Type Bits/KeyID Date User ID
pub 1024D/22458A98 2000-07-10 Linux Mandrake Security Team
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