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Category:   Application (E-mail Server)  >   Fetchmail Vendors:   Raymond, Eric S.
(Red Hat Issues Fix) Fetchmail Executes Arbitrary Code Supplied By Remote Servers
SecurityTracker Alert ID:  1002387
SecurityTracker URL:
CVE Reference:   GENERIC-MAP-NOMATCH   (Links to External Site)
Date:  Sep 11 2001
Impact:   Execution of arbitrary code via network, User access via network
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): prior to 5.8.17
Description:   A memory modification vulnerability was reported in Fetchmail, allowing remote users to execute arbitrary code on the fetchmail server in certain situations.

It is reported that flaws in the pop3.c and imap.c files allow a remote user to 'poke' arbitrary memory addresses with 32 bit data. A remote user that is impersonating a POP3 or IMAP server that fetchmail queries can trigger this vulnerability. If the remote user can spoof the fetchmail server's DNS, then the remote user can potentially trigger the vulnerability without impersonating the POP3 or IMAP mail server.

Some demonstration exploit code is included in the Source Message.

Impact:   A remote user can cause fetchmail to execute arbitrary code with the privileges of the user account running fetchmail.
Solution:   The vendor has released a fix. See the Source Message for the vendor's advisory containing directions on how to obtain the appropriate fix.
Vendor URL: (Links to External Site)
Cause:   Input validation error
Underlying OS:  Linux (Red Hat Linux)

Message History:   This archive entry is a follow-up to the message listed below.
Aug 11 2001 Fetchmail Executes Arbitrary Code Supplied By Remote Servers

 Source Message Contents

Subject:  [RHSA-2001:103-04] Updated fetchmail packages available

                   Red Hat, Inc. Red Hat Security Advisory

Synopsis:          Updated fetchmail packages available
Advisory ID:       RHSA-2001:103-04
Issue date:        2001-08-23
Updated on:        2001-09-06
Product:           Red Hat Linux
Keywords:          fetchmail array index bounds
Cross references:  
Obsoletes:         RHBA-2000:106

1. Topic:

Updated fetchmail packages are now available for Red Hat Linux 5.2, 6.2, 7,
and 7.1.  These packages close a remotely-exploitable vulnerability in

2. Relevant releases/architectures:

Red Hat Linux 5.2 - alpha, i386, sparc

Red Hat Linux 6.2 - alpha, i386, sparc

Red Hat Linux 7.0 - alpha, i386

Red Hat Linux 7.1 - alpha, i386, ia64

3. Problem description:

Fetchmail versions up to 5.8.9 are susceptible to remote attacks from
malicious servers.  When fetchmail attempts to create an index of messages
in the remote mailbox being polled, it uses index numbers sent by the
server as an index into an internal array.  If a server sends fetchmail a
negative number, fetchmail will attempt to write data outside the bounds of
the array.

4. Solution:

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

To update all RPMs for your particular architecture, run:

rpm -Fvh [filenames]

where [filenames] is a list of the RPMs you wish to upgrade.  Only those
RPMs which are currently installed will be updated.  Those RPMs which are
not installed but included in the list will not be updated.  Note that you
can also use wildcards (*.rpm) if your current directory *only* contains the
desired RPMs.

Please note that this update is also available via Red Hat Network.  Many
people find this an easier way to apply updates.  To use Red Hat Network,
launch the Red Hat Update Agent with the following command:


This will start an interactive process that will result in the appropriate
RPMs being upgraded on your system.

5. Bug IDs fixed ( for more info):

6. RPMs required:

Red Hat Linux 5.2:





Red Hat Linux 6.2:





Red Hat Linux 7.0:




Red Hat Linux 7.1:





7. Verification:

MD5 sum                           Package Name
7503b049db6ff4f1474f226d274fe92d 5.2/en/os/SRPMS/fetchmail-5.9.0-0.5.1.src.rpm
31a45847fced4be1adcde11e9f2aa757 5.2/en/os/alpha/fetchmail-5.9.0-0.5.1.alpha.rpm
e9eb76daa617641fcb3632fdbc5e4dac 5.2/en/os/alpha/fetchmailconf-5.9.0-0.5.1.alpha.rpm
ebda08b540c02b2db58cbccde1d99f40 5.2/en/os/i386/fetchmail-5.9.0-0.5.1.i386.rpm
7619346da94d964d51af89df1dc89f18 5.2/en/os/i386/fetchmailconf-5.9.0-0.5.1.i386.rpm
446347177fbf9caf0fc9cea8756ccea9 5.2/en/os/sparc/fetchmail-5.9.0-0.5.1.sparc.rpm
fabd00863865631c986c80e49b088f55 5.2/en/os/sparc/fetchmailconf-5.9.0-0.5.1.sparc.rpm
b74380ba52b3ff09d53040a3bd18abfb 6.2/en/os/SRPMS/fetchmail-5.9.0-0.6.2.src.rpm
d7a2cd0a97ea5265b413921a2e6fcd8c 6.2/en/os/alpha/fetchmail-5.9.0-0.6.2.alpha.rpm
26ea94e37d0d88823e0f85a3e2c07ef4 6.2/en/os/alpha/fetchmailconf-5.9.0-0.6.2.alpha.rpm
3217a12fcf834f1a94b22e3a1f998899 6.2/en/os/i386/fetchmail-5.9.0-0.6.2.i386.rpm
bd70942262b151a416111483612d7991 6.2/en/os/i386/fetchmailconf-5.9.0-0.6.2.i386.rpm
e62237b1adef610f52192d1b9fbbfc67 6.2/en/os/sparc/fetchmail-5.9.0-0.6.2.sparc.rpm
88966042a39e1ff9b344774bff6f8df6 6.2/en/os/sparc/fetchmailconf-5.9.0-0.6.2.sparc.rpm
43dd892f01a53615826fd05d5c5d9182 7.0/en/os/SRPMS/fetchmail-5.9.0-0.7.1.src.rpm
1edf22a362dda414de5f1a9a437308d8 7.0/en/os/alpha/fetchmail-5.9.0-0.7.1.alpha.rpm
2f594d9a083f553e4b0f10e5f866c621 7.0/en/os/alpha/fetchmailconf-5.9.0-0.7.1.alpha.rpm
50d7a9d1276701fc425a6bc42d9e4e95 7.0/en/os/i386/fetchmail-5.9.0-0.7.1.i386.rpm
77e22d5c9d02d26ba9013df9e25ee71d 7.0/en/os/i386/fetchmailconf-5.9.0-0.7.1.i386.rpm
43dd892f01a53615826fd05d5c5d9182 7.1/en/os/SRPMS/fetchmail-5.9.0-0.7.1.src.rpm
1edf22a362dda414de5f1a9a437308d8 7.1/en/os/alpha/fetchmail-5.9.0-0.7.1.alpha.rpm
2f594d9a083f553e4b0f10e5f866c621 7.1/en/os/alpha/fetchmailconf-5.9.0-0.7.1.alpha.rpm
50d7a9d1276701fc425a6bc42d9e4e95 7.1/en/os/i386/fetchmail-5.9.0-0.7.1.i386.rpm
77e22d5c9d02d26ba9013df9e25ee71d 7.1/en/os/i386/fetchmailconf-5.9.0-0.7.1.i386.rpm
e6900c3bdd22ed841ce0c681e5bf8942 7.1/en/os/ia64/fetchmail-5.9.0-0.7.1.ia64.rpm
911f4ea0e059f39695583e3af90992b5 7.1/en/os/ia64/fetchmailconf-5.9.0-0.7.1.ia64.rpm

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

You can verify each package with the following command:
    rpm --checksig  <filename>

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 <filename>

8. References:

Copyright(c) 2000, 2001 Red Hat, Inc.

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