Paul Wouters of Red Hat reports:

The Libreswan Project was notified by Iustina Melinte of a vulnerability
regarding dereferencing of non-received IKEv2 payloads. This allows
a malicious non-authenticated remote user to cause the libreswan IKE
daemon to restart.

Vulnerable versions: libreswan up to version 3.7
Not vulnerable     : libreswan 3.8

If you cannot upgrade to 3.8, please see the above link for a patch for this issue.

All versions of openswan including 2.6.39 are also vulnerable to this bug, see CVE-2013-6466

Vulnerability information
--------------------------

Iustina Melinte used a custom IKE fuzzer to test libreswan. By withholding
or renumbering certain IKEv2 payloads, the pluto IKE daemon crashes while
trying to dereference a NULL pointer on the presumably received payload.

Configurations that only allow IKEv1 are not vulnerable.

Exploitation
-------------

This denial of service can be launched by anyone using a few mangled
IKEv2 packets. No authentication credentials are required. No remote code
execution is possible through this vulnerability. Libreswan automatically
restarts when it crashes. Please note that this will also cause existing 
connections to drop.

Workaround
-----------

When not requiring or using IKEv2, adding the keyword ikev2=never to
all connections enforced that only IKEv1 can be used. This prevents the
affected code from being called. The default value for ikev2= is "yes",
meaning that IKEv2 is allowed and the affected code can be triggered causing
a denial-of-service. 

Credits
--------

This vulnerability was found by Iustina Melinte. The Libreswan Project is
especially thankful for Iustina's assistance with the IKE fuzzer software.