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Screen: UTF-8 character handling vulnerability


1.  Gentoo Linux Security Advisory

Version Information

Advisory Reference GLSA 200611-01 / screen
Release Date November 03, 2006
Latest Revision November 03, 2006: 01
Impact high
Exploitable remote
Package Vulnerable versions Unaffected versions Architecture(s)
app-misc/screen < 4.0.3 >= 4.0.3 All supported architectures

Related bugreports: #152770


Screen contains an error in its UTF-8 character handling code that would allow a remote Denial of Service or possibly the remote execution of arbitrary code.

2.  Impact Information


Screen is a full-screen window manager that multiplexes a physical terminal between several processes, typically interactive shells.


cstone and Richard Felker discovered a flaw in Screen's UTF-8 combining character handling.


The vulnerability can be exploited by writing a special string of characters to a Screen window. A remote attacker could cause a Denial of Service or possibly execute arbitrary code with the privileges of the user running Screen through a program being run inside a Screen session, such as an IRC client or a mail client.

3.  Resolution Information


There is no known workaround at this time.


All Screen users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=app-misc/screen-4.0.3"

4.  References


Page updated November 03, 2006

Summary: This is a Gentoo Linux Security Advisory

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