Screen: UTF-8 character handling vulnerability

1. Gentoo Linux Security Advisory

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

Synopsis

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

Background

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

Description

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

Impact

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

Workaround

There is no known workaround at this time.

Resolution

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

CVE-2006-4573

Page updated November 03, 2006

Summary: This is a Gentoo Linux Security Advisory

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