In NetX HTTP server functionality of Eclipse ThreadX NetX Duo before version 6.4.2, an attacker can cause an integer underflow and a subsequent denial of service by writing a very large file, by specially crafted packets with Content-Length in one packet smaller than the data request size of the other packet. A possible workaround is to disable HTTP PUT support.
The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.