CURL-CVE-2017-8816

libcurl contains a buffer overrun flaw in the NTLM authentication code.

The internal function Curl_ntlm_core_mk_ntlmv2_hash sums up the lengths of the username + password (= SUM) and multiplies the sum by two (= SIZE) to figure out how large storage to allocate from the heap.

The SUM value is subsequently used to iterate over the input and generate output into the storage buffer. On systems with a 32 bit size_t, the math to calculate SIZE triggers an integer overflow when the combined lengths of the username and password is larger than 2GB (2^31 bytes). This integer overflow usually causes a very small buffer to actually get allocated instead of the intended very huge one, making the use of that buffer end up in a buffer overrun.