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FreeBSD Ports Security Advisory: popper port contains remote vulnerability [REVISED]

Jul 13, 2000, 19:45 (0 Talkback[s])


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Date: Tue, 11 Jul 2000 14:55:37 -0700
From: FreeBSD Security Advisories security-advisories@freebsd.org
Subject: FreeBSD Ports Security Advisory: FreeBSD-SA-00:26.popper [REVISED]


FreeBSD-SA-00:26                                           Security Advisory
                                                                FreeBSD, Inc.

Topic:          popper port contains remote vulnerability [REVISED]

Category:       ports
Module:         popper
Announced:      2000-07-05
Revised:        2000-07-11
Credits:        Prizm 
Affects:        Ports collection.
Corrected:      2000-05-25
Vendor status:  Notified
FreeBSD only:   NO
I. Background

QPopper is a popular POP3 mail server.

II. Problem Description

The qpopper port, version 2.53 and earlier, incorrectly parses string formatting operators included in part of the email message header. A remote attacker can send a malicious email message to a local user which can cause arbitrary code to be executed on the server when a POP client retrieves the message using the UIDL command. The code is executed as the user who is retrieving mail: thus if root reads email via POP3 this can lead to a root compromise. This vulnerability is not present in qpopper-3.0.2, also available in FreeBSD ports.

The qpopper 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 3500 third-party applications in a ready-to-install format. The ports collection shipped with FreeBSD 4.0 contains this problem since it was discovered after the release, but it was fixed in time for FreeBSD 3.5.

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.

III. Impact

Remote users can cause arbitrary code to be executed as the retrieving user when a POP client retrieves email.

If you have not chosen to install the qpopper-2.53 port/package, then your system is not vulnerable to this problem.

IV. Workaround

Deinstall the qpopper-2.53 port/package, if you you have installed it.

V. Solution

One of the following:

1) Upgrade your entire ports collection and rebuild the qpopper port, or upgrade to qpopper-3.0.2 available in /usr/ports/mail/popper3.

2) Deinstall the old package and install a new package dated after the correction date, obtained from:



3) download a new port skeleton for the qpopper 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:


VI. Revision History

v1.0  2000-07-05  Initial release
v1.1  2000-07-11  Correct URL of qpopper-2.53 package and note availability of
                  qpopper3-3.0.2. Update size of ports collection.

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