GLSA 200405-07: Exim verify=header_syntax buffer overflow

http://security.gentoo.org/

Severity:	high
Title:	Exim verify=header_syntax buffer overflow
Date:	05/14/2004
Bugs:	#50217
ID:	200405-07

Synopsis

When the verify=header_syntax option is set, there is a buffer overflow in Exim that allows remote execution of arbitrary code.

Background

Exim is an highly configurable message transfer agent (MTA) developed at the University of Cambridge.

Affected packages

Package	Vulnerable	Unaffected	Architecture(s)
mail-mta/exim	<= 4.33	>= 4.33-r1	All supported architectures

Description

When the option "verify = header_syntax" is used in an ACL in the configuration file, Exim is vulnerable to a buffer overflow attack that can be triggered remotely by sending malicious headers in an email message. Note that this option is not enabled in Exim's default configuration file.

Impact

This vulnerability can be exploited to trigger a denial of service attack and potentially execute arbitrary code with the rights of the user used by the Exim daemon (by default this is the "mail" user in Gentoo Linux).

Workaround

Make sure the verify=header_syntax option is not used in your exim.conf file.

Resolution

All users of Exim should upgrade to the latest stable version:

    # emerge sync

    # emerge -pv ">=mail-mta/exim-4.33-r1"
    # emerge ">=mail-mta/exim-4.33-r1"

References

CAN-2004-0400

Availability

This GLSA and any updates to it are available for viewing at the Gentoo Security Website: http://security.gentoo.org/glsa/glsa-200405-07.xml

Concerns?

Security is a primary focus of Gentoo Linux and ensuring the confidentiality and security of our users machines is of utmost importance to us. Any security concerns should be addressed to security@gentoo.org or alternatively, you may file a bug at https://bugs.gentoo.org.