net/core/net_namespace.c in the Linux kernel 2.6.32 and earlier does not properly handle a high rate of creation and cleanup of network namespaces, which makes it easier for remote attackers to cause a denial of service (memory consumption) via requests to a daemon that requires a separate namespace per connection, as demonstrated by vsftpd.
bugs.debian.org/cgi-bin/bugreport.cgi?bug=629373
git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git%3Ba=commit%3Bh=2b035b39970740722598f7a9d548835f9bdd730f
git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git%3Ba=commit%3Bh=f875bae065334907796da12523f9df85c89f5712
ie.archive.ubuntu.com/linux/kernel/v2.6/ChangeLog-2.6.33
kerneltrap.org/mailarchive/git-commits-head/2009/12/8/15289
neil.brown.name/git?p=linux-2.6%3Ba=patch%3Bh=2b035b39970740722598f7a9d548835f9bdd730f
patchwork.ozlabs.org/patch/88217/
www.debian.org/security/2011/dsa-2305
www.openwall.com/lists/oss-security/2011/06/06/10
www.openwall.com/lists/oss-security/2011/06/06/20
www.ubuntu.com/usn/USN-1288-1
bugs.launchpad.net/ubuntu/+source/linux/+bug/720095
bugzilla.redhat.com/show_bug.cgi?id=711134
bugzilla.redhat.com/show_bug.cgi?id=711245