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Date: Thu, 12 Feb 2009 18:55:11 +0100
From: Jan Lieskovsky <>
Cc: "Steven M. Christey" <>
Subject: Re: CVE Request -- net-snmp (sensitive host
	information disclosure)


  thanks for the assignment!

On Thu, 2009-02-12 at 10:56 -0500, Steven M. Christey wrote:
> I'm confused by the upstream diff being referenced by the Red Hat bug ID.
> Specifically, it looks like some sprintf's got changed, and the result is
> used for logging.  Is it certain that the attacker can bypass
> authorization, or is net-snmp just mis-reporting it?

Yes, the fix looks strange, but it resolves the issue (checked for
net-snmp-5.4.2). Looks like net-snmp is mis-reporting
the results, so subsequent parsing performed by tcp_wrappers
fails so hosts, for whose the snmp responses should be
forbidden, are getting them regardless of /etc/hosts.deny

More exact explanation from our pkg-maintainer:


So... the bug is in net-snmp, it mixes source and destination IP 
addresses, which renders tcp_wrappers support in snmpd completely 
useless (it checks destination IP addr instead of source IP address).


Not sure here, if the CVE description should be modified appropriately?

Regards, Jan.
Jan iankko Lieskovsky / Red Hat Security Response Team

> I'm going with authorization bypass at the moment.
> ======================================================
> Name: CVE-2008-6123
> Status: Candidate
> URL:
> Reference: MLIST:[oss-security] 20090212 CVE Request -- net-snmp (sensitive host information disclosure)
> Reference: URL:
> Reference: CNFIRM:
> Reference: CONFIRM:
> Reference: CONFIRM:
> Reference: MISC:
> The netsnmp_udp_fmtaddr function (snmplib/snmpUDPDomain.c) in net-snmp
> 5.0.9 through 5.4.2, when using TCP wrappers for client authorization,
> does not properly parse hosts.allow rules, which allows remote
> attackers to bypass intended access restrictions and execute SNMP
> queries, related to "source/destination IP address confusion."

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