Red Hat Security Advisory: File access problems in lpr/lpd

Date: Mon, 25 Oct 1999 11:48:26 -0400
From: Bill Nottingham [email protected]
To: [email protected]

Red Hat, Inc. Security Advisory

Synopsis: File access problems in lpr/lpd
Advisory ID: RHSA-1999:041-03
Issue date: 1999-10-17
Updated on: 1999-10-25
Keywords: lpr lpd permissions
Cross references:

Revision History:
1999-10-19: New packages, to fix a remote printing bug.
Add note about local printing fix for Red Hat Linux 6.1.
1999-10-25: New packages, to fix problems introduced by the
security fix.

1. Topic:

There are potential problems with file access checking in the
lpr and lpd programs. These could allow users to potentially print
files they do not have access to. Also, there are bugs in remote
printing in the lpd that shipped with Red Hat Linux 6.1.

2. Bug IDs fixed (http://developer.redhat.com/bugzilla
for more info):

5122 5540 5697 5832 5835 5903 5949

3. Relevant releases/architectures:

Red Hat Linux 4.x, all architectures
Red Hat Linux 5.x, all architectures
Red Hat Linux 6.x, all architectures

4. Obsoleted by:

5. Conflicts with:

6. RPMs required:

Red Hat Linux 4.x:




Source packages:

Red Hat Linux 5.x:




Source packages:




Source packages:

7. Problem description:

There are two problems in the lpr and lpd programs. By
exploiting a race between the access check and the actual file
opening, it is potentially possible to have lpr read a file as root
that the user does not have access to. Also, the lpd program would
blindly open queue files as root; by use of the ‘-s’ flag to lpr,
it was possible to have lpd print files that the user could not

Thanks go to Tymm Twillman for pointing out these

Also, various bugs in remote printing that were present in the
lpd released with Red Hat Linux 6.1 have been fixed.

Another problem with remote printing was fixed in lpr-0.44. If you
are experiencing problems with remote printing in the previous
errata update, it is recommended that you upgrade. There are no
known security issues with the previous errata packages.

If you are experiencing problems with local printing in Red Hat
Linux 6.1, make sure that you have:

alias parport_lowlevel parport_pc

in your /etc/conf.modules file.

The original security patch broke some aspects of printing. New
errata RPMs are available which should fix the problem.

8. Solution:

For each RPM for your particular architecture, run:

rpm -Uvh

where filename is the name of the RPM.

9. Verification:

MD5 sum Package Name

3ac16788d027447679cf6bf5e6483574  lpr-0.46-0.4.2.src.rpm
78b9f5c8538d382c24fbe303c1e05858  lpr-0.46-0.4.2.alpha.rpm
daffbab440b7dbabd233904a75e3bb82  lpr-0.46-0.4.2.i386.rpm
def0c894a62875e809b5693c09393931  lpr-0.46-0.4.2.sparc.rpm

91635732bdf133068543f18887b4eb9d  lpr-0.46-0.5.2.src.rpm
cd5575ca2c159f30beff740709699992  lpr-0.46-0.5.2.alpha.rpm
756d445db7803b0db3a5f8b19dca0702  lpr-0.46-0.5.2.i386.rpm
c064b331ac84d67714fe46913b3669c5  lpr-0.46-0.5.2.sparc.rpm

03c996550636cbe4ca0a9fc853f969b6  lpr-0.46-1.src.rpm
30089f82ecf8e8a89565c5bba361697d  lpr-0.46-1.alpha.rpm
a01c0b9278c2c9ffb4bb6450703fc124  lpr-0.46-1.i386.rpm
41a1ef221a15446ed46b54092d7c14ca  lpr-0.46-1.sparc.rpm

These packages are signed with GnuPG by Red Hat Inc. for
security. Our key is available at:


You can verify each package with the following command:

rpm –checksig

If you only wish to verify that each package has not been
corrupted or tampered with, examine only the md5sum with the
following command:

rpm –checksig –nogpg

Note that you need RPM >= 3.0 to check GnuPG keys.

10. References: