The "cache update reply processing" functionality in Squid 2.x before 2.6.STABLE17 and Squid 3.0 allows remote attackers to cause a denial of service (crash) via unknown vectors related to HTTP headers and an Array memory leak during requests for cached objects.
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.