AdaCore Ada Web Services (AWS) before 2.10.2 computes hash values for form parameters without restricting the ability to trigger hash collisions predictably, which allows remote attackers to cause a denial of service (CPU consumption) by sending many crafted parameters.
http://www.ocert.org/advisories/ocert-2011-003.html
http://www.nruns.com/_downloads/advisory28122011.pdf
http://www.adacore.com/2012/01/27/security-advisory-sa-2012-l119-003-hash-collisions-in-aws/
http://archives.neohapsis.com/archives/bugtraq/2012-01/0169.html