Lynx: Arbitrary command execution

Background

Lynx is a fully-featured WWW client for users running cursor-addressable, character-cell display devices such as vt100 terminals and terminal emulators.

Description

iDefense labs discovered a problem within the feature to execute local cgi-bin programs via the “lynxcgi:” URI handler. Due to a configuration error, the default settings allow websites to specify commands to run as the user running Lynx.

Impact

A remote attacker can entice a user to access a malicious HTTP server, causing Lynx to execute arbitrary commands.

Workaround

Disable “lynxcgi” links by specifying the following directive in lynx.cfg:

TRUSTED_LYNXCGI:none

Resolution

All Lynx users should upgrade to the latest version:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=www-client/lynx-2.8.5-r2"