multipart/parser.rb in Rack 1.3.x before 1.3.8 and 1.4.x before 1.4.3 allows remote attackers to cause a denial of service (memory consumption and out-of-memory error) via a long string in a Multipart HTTP packet.
Improper Restriction of Operations within the Bounds of a Memory Buffer The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary.