LibVNCServer: Authentication bypass

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200608-05 / libvncserver
Release Date	August 04, 2006
Latest Revision	August 04, 2006: 01
Impact	high
Exploitable	remote

Package	Vulnerable versions	Unaffected versions	Architecture(s)
net-libs/libvncserver	< 0.8.2	>= 0.8.2	All supported architectures

Related bugreports: #136916

Synopsis

VNC servers created with LibVNCServer accept insecure protocol types, even when the server does not offer it, resulting in unauthorized access to the server.

2. Impact Information

Background

LibVNCServer is a GPL'ed library for creating VNC servers.

Description

LibVNCServer fails to properly validate protocol types effectively letting users decide what protocol to use, such as "Type 1 - None". LibVNCServer will accept this security type, even if it is not offered by the server.

Impact

An attacker could use this vulnerability to gain unauthorized access with the privileges of the user running the VNC server.

3. Resolution Information

Workaround

There is no known workaround at this time.

Resolution

All LibVNCServer users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=net-libs/libvncserver-0.8.2"

4. References

CVE-2006-2450

Page updated August 04, 2006

Summary: This is a Gentoo Linux Security Advisory

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