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Family: Gentoo Local Security Checks --> Category: infos

[GLSA-200402-02] XFree86 Font Information File Buffer Overflow Vulnerability Scan

Vulnerability Scan Summary
XFree86 Font Information File Buffer Overflow

Detailed Explanation for this Vulnerability Test
The remote host is affected by the vulnerability described in GLSA-200402-02
(XFree86 Font Information File Buffer Overflow)

Exploitation of a buffer overflow in The XFree86 Window System
discovered by iDefence allows local attackers to gain root
The problem exists in the parsing of the 'font.alias' file. The X
server (running as root) fails to check the length of the user
provided input, so a malicious user may craft a malformed
'font.alias' file causing a buffer overflow upon parsing,
eventually leading to the execution of arbitrary code.
To reproduce the overflow on the command line one can run:
# cat > fonts.dir < 1
word.bdf -misc-fixed-medium-r-semicondensed--13-120-75-75-c-60-iso8859-1
# perl -e 'print "0" x 1024 . "A" x 96 . "\n"' > fonts.alias
# X :0 -fp $PWD
{Some output removed}... Server aborting... Segmentation fault (core dumped)


Successful exploitation can lead to a root compromise provided
that the attacker is able to execute commands in the X11
subsystem. This can be done either by having console access to the
target or through a remote exploit against any X client program
such as a web-browser, mail-reader or game.


No immediate workaround is available
a software upgrade is required.
Gentoo has released XFree 4.2.1-r3, 4.3.0-r4 and and
encourages all users to upgrade their XFree86
installations. Vulnerable versions are no longer available in


All users are recommended to upgrade their XFree86 installation:
# emerge sync
# emerge -pv x11-base/xfree
# emerge x11-base/xfree

Threat Level: High

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