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leafnode 1.9.3 - 1.9.41 security announcement SA-2003-01
Sep 04 2003 01:19AM
Matthias Andree (matthias andree gmx de)
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Topic: potential denial of service in leafnode
Writer: Matthias Andree
Type: potential denial of service
Impact: fetchnews hangs, no new fetchnews/texpire processes
can be started
Credits: Joshua Crawford (for sending a precise bug report)
- only one process will clog memory since leafnode-1.9.20
bug can hang for an extended amount of time
- no privilege escalation through this bug
Affects: leafnode 1.9.3 (1999) up to 1.9.41 (2003)
Not affected: leafnode 1.9.42 and newer
Default install: affected.
Introduced: between 1999-03-03 and 1999-07-15 (no precise date found)
1999-07-15 07:49 leafnode 1.9.3 announced by Cornelius Krasel
Corrected: 2003-06-20 22:57:48 UTC (CVS) - committed corrected version
2003-06-27 11:29 leafnode 1.9.42 released
0. Release history
2003-09-02 1.00 initial announcement
2003-09-04 1.01 mention leafnode 1.9.43 in body text, drop appendix A
leafnode is a store-and-forward proxy for Usenet news, is uses the
network news transfer protocol (NNTP). It consists of several
collaborating programs, the server part is usually started by inetd,
xinetd or tcpserver, the client part is usually started by cron or
This security announcement pertains to leafnode-1, the stable branch.
The leafnode-2 development branch has not yet seen a stable release, so
it is not subject to security announcements.
2. Problem description
A vulnerability was found in the fetchnews program (the NNTP client) that
may under some circumstances cause wait for input that never arrives,
fetchnews "hangs". This hang does not cost CPU.
This bug was not deemed security relevant at first, but as it can
be triggered from the outside, by providing malformatted (non-RFC-1036)
Usenet news articles, and because it then stops unattended systems from
functioning, it was decided to release this security announcement.
As only one fetchnews program can run at a time, subsequently started
fetchnews and texpire programs will terminate immediately. This means
that the news base will no longer be updated, older articles will no
longer expire, until the hanging fetchnews process gets unstuck, usually
through a manual "kill" command or a reboot.
No reliable workaround possible.
NOTE: Killing fetchnews before completion leaves stale data on disk and
is therefore not deemed reliable, although it relieves the immediate
"cannot start texpire or fetchnews" condition.
Upgrade your leafnode package to version 1.9.42 or later.
At this time, leafnode 1.9.43 is the up-to-date stable release.
Note that leafnode 1.9.X versions are deemed stable, and it is usually
best to go for the latest released 1.9.X version to have all the other
bug fixes as well. No broken-out version of this patch will be
provided, distributors are urged to update to the latest leafnode
leafnode 1.9.43 is available from sourceforge:
This policy of not providing a broken-out patch may generate a conflict
with some distribution's post-release update policies.
As the current leafnode maintainer, I do not have financial and time
ressources to provide support for any but the latest released version.
People keep reporting bugs about leafnode-1.9.33, 1.9.24 or 1.9.19,
which is a waste of time for the user and the leafnode maintainer.
6. Solution details
date: 2003/06/20 22:57:48; author: emma; state: Exp; lines: +10 -4
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