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AUSCERT External Security Bulletin Redistribution
ESB-2001.288 -- FreeBSD-SA-01:43.fetchmail
fetchmail contains potentially exploitable buffer overflow
12 July 2001
AusCERT Security Bulletin Summary
Vendor: FreeBSD Ports Collection
Operating System: FreeBSD
Impact: Execute Arbitrary Code/Commands
Denial of Service
Access Required: Remote
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FreeBSD-SA-01:43 Security Advisory
Topic: fetchmail contains potentially exploitable buffer
Credits: Wolfram Kleff <firstname.lastname@example.org>
Affects: Ports collection prior to the correction date.
Vendor status: Updated version released
FreeBSD only: NO
fetchmail is a program used to retrieve email from POP and IMAP
II. Problem Description
The fetchmail port, versions prior to fetchmail-5.8.6, contains a
potentially exploitable buffer overflow when rewriting headers
longer than 512 bytes. This problem may allow remote users to
cause fetchmail to crash and potentially execute arbitrary code
as the user running fetchmail.
The fetchmail port is not installed by default, nor is it "part of
FreeBSD" as such: it is part of the FreeBSD ports collection, which
contains over 5400 third-party applications in a ready-to-install
format. The ports collection shipped with FreeBSD 4.3 is vulnerable
to this problem since it was discovered after its release.
FreeBSD makes no claim about the security of these third-party
applications, although an effort is underway to provide a security
audit of the most security-critical ports.
Remote users using specially crafted email messages may be able to
cause fetchmail to crash and potentially execute arbitrary code as
the user running fetchmail.
If you have not chosen to install the fetchmail port/package, then
your system is not vulnerable to this problem.
Deinstall the fetchmail port/package if you have installed it.
One of the following:
1) Upgrade your entire ports collection and rebuild the fetchmail port.
2) Deinstall the old package and install a new package dated after the
correction date, obtained from the following directories:
Packages are not automatically generated for the alpha architecture at
this time due to lack of build resources.
3) download a new port skeleton for the fetchmail port from:
and use it to rebuild the port.
4) Use the portcheckout utility to automate option (3) above. The
portcheckout port is available in /usr/ports/devel/portcheckout or the
package can be obtained from:
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