Multiple stack consumption vulnerabilities in the kernel in NetBSD 4.0, 5.0 before 5.0.3, and 5.1 before 5.1.1, when IPsec is enabled, allow remote attackers to cause a denial of service (memory corruption and panic) or possibly have unspecified other impact via a crafted (1) IPv4 or (2) IPv6 packet with nested IPComp headers.
http://www.kb.cert.org/vuls/id/668220
http://lists.grok.org.uk/pipermail/full-disclosure/2011-April/080031.html
http://ftp.netbsd.org/pub/NetBSD/security/advisories/NetBSD-SA2011-004.txt.asc