Software Engineering Institute

CUPS is a cross-platform printing system for UNIX environments. It can use the IPP, LPD, SMB, and JetDirect protocols to interact with printers. The SMB protocol is used to communicate with printers that are shared via Microsoft Windows or other SMB-compatible software such as Samba. When an SMB printer is added or modified, the connection string for the printer is written to the log file in plain text. This connection string will contain a username and password if authentication is required for the printer.

A local authenticated user may be able to retrieve the usernames and passwords for other accounts.

Apply a patch from your vendor

For vendor-specific information regarding vulnerable status and patch availability, please see the Systems Affected section of this document.

Upgrade your version of CUPS

This issue is resolved in CUPS 1.1.22rc1. Starting with this version, the connection string for the printer is sanitized so that it does not contain sensitive information.

Restrict access to the CUPS log file

By default, the CUPS log file is world-readable. Access to the CUPS log file can be restricted by setting the LogFilePerm option in cupsd.conf to "0600"

Do not use authenticated printing to Windows via Samba

Because of the possibility of disclosing sensitive information when using a printer shared via SMB, it is suggested to use other protocols such as LPD. Windows can function as an LPD server when Print Services for UNIX is installed.