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Category:   OS (UNIX)  >   NetBSD Vendors:   NetBSD
NetBSD ICMPv6 Processing Flaw Lets Remote Users Deny Service
SecurityTracker Alert ID:  1021111
SecurityTracker URL:
CVE Reference:   CVE-2008-3530   (Links to External Site)
Date:  Oct 28 2008
Impact:   Denial of service via network
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): 3.0, 3.1, 4.0
Description:   A vulnerability was reported in the NetBSD kernel's IPv6 stack. A remote user can cause denial of service conditions.

A remote user can send a specially crafted ICMPv6 'Packet Too Big Message' to trigger a kernel panic.

Systems configured to process IPv6 packets that have active IPv6 TCP sockets are affected.

Tom Parker and Bjoern A. Zeeb reported this vulnerability.

Impact:   A remote user can cause the target system to crash.
Solution:   The vendor has issued a source code fix.

The vendor's advisory is available at:

Vendor URL: (Links to External Site)
Cause:   Input validation error

Message History:   None.

 Source Message Contents

Subject:  NetBSD Security Advisory 2008-015: ICMPv6 Packet Too Big messages

Hash: SHA1

		 NetBSD Security Advisory 2008-015

Topic:		ICMPv6 Packet Too Big messages

Version:	NetBSD-current:		affected
		NetBSD 4.0.*:		not affected
		NetBSD 4.0:		affected
		NetBSD 3.1.*:		affected
		NetBSD 3.1:		affected
		NetBSD 3.0.*:		affected
		NetBSD 3.0:		affected

Severity:	Denial of service

Fixed:		NetBSD-current:		October 03, 2008
		NetBSD-4-0 branch:	October 03, 2008
			(4.0.1 includes the fix)
		NetBSD-4 branch:	October 03, 2008
			(4.1 will include the fix)
		NetBSD-3-1 branch:	October 03, 2008
			(3.1.2 will include the fix)
		NetBSD-3-0 branch:	October 03, 2008
			(3.0.4 will include the fix)
		NetBSD-3 branch:	October 03, 2008
			(3.2 will include the fix)


An error may occur while processing ICMPv6 'Packet Too Big' (RFC 2463) 
messages which may result in a denial of service (system panic).

This vulnerability has been assigned CVE-2008-3530.

Technical Details

An error can occur when processing the proposed MTU of an ICMPv6 
'Packet Too Big' message.

Solutions and Workarounds

Only kernels compiled with the following option are vulnerable to this issue:

	options INET6

As a temporary workaround recompile the kernel with the above option 
commented out.  The default NetBSD GENERIC kernels have this
option enabled.

For all NetBSD versions, you need to obtain fixed kernel sources,
rebuild and install the new kernel, and reboot the system.
The fixed source may be obtained from the NetBSD CVS repository.        
The following instructions briefly summarise how to upgrade your        
kernel.  In these instructions, replace:

  ARCH     with your architecture (from uname -m), and                  
  KERNCONF with the name of your kernel configuration file.    

To update from CVS, re-build, and re-install the kernel:

        # cd src
        # cvs update -d -P sys/netinet6/icmp6.c
        # ./ kernel=KERNCONF
        # mv /netbsd /netbsd.old
        # cp sys/arch/ARCH/compile/obj/KERNCONF/netbsd /netbsd 
        # shutdown -r now

For more information on how to do this, see:

Thanks To

Matt Thomas for the fix and FreeBSD for initial analysis of the issue.

Revision History

	2008-10-27	Initial release

More Information

Advisories may be updated as new information becomes available.
The most recent version of this advisory (PGP signed) can be found at

Information about NetBSD and NetBSD security can be found at and

Copyright 2008, The NetBSD Foundation, Inc.  All Rights Reserved.
Redistribution permitted only in full, unmodified form.

$NetBSD: NetBSD-SA2008-015.txt,v 1.4 2008/10/27 19:47:21 adrianp Exp $

Version: GnuPG v1.4.9 (NetBSD)



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