Walrus in Eucalyptus before 3.2.2 allows remote attackers to cause a denial of service (memory, thread, and CPU consumption) via a crafted XML message containing a DTD, as demonstrated by a bucket-logging request.
https://eucalyptus.atlassian.net/browse/EUCA-5277
http://www.eucalyptus.com/resources/security/advisories/esa-09