w3m: Format string vulnerability

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200701-06 / w3m
Release Date	January 12, 2007
Latest Revision	January 12, 2007: 01
Impact	normal
Exploitable	remote

Package	Vulnerable versions	Unaffected versions	Architecture(s)
www-client/w3m	< 0.5.1-r4	>= 0.5.1-r4	All supported architectures

Related bugreports: #159145

Synopsis

w3m does not correctly handle format string specifiers in SSL certificates.

2. Impact Information

Background

w3m is a multi-platform text-based web browser.

Description

w3m in -dump or -backend mode does not correctly handle printf() format string specifiers in the Common Name (CN) field of an X.509 SSL certificate.

Impact

An attacker could entice a user to visit a malicious website that would load a specially crafted X.509 SSL certificate containing "%n" or other format string specifiers, possibly resulting in the execution of arbitrary code with the rights of the user running w3m.

3. Resolution Information

Workaround

There is no known workaround at this time.

Resolution

All w3m users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=www-client/w3m-0.5.1-r4"

4. References

CVE-2006-6772

Updated January 12, 2007

Summary: This is a Gentoo Linux Security Advisory

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