Improper Input Validation
When curl versions from 4.9 through 7.84.0 used to retrieve and parse cookies from a HTTP(S) server, it accepts cookies using control codes that when later are sent back to a HTTPserver might make the server return 400 responses. Effectively allowing a "sister site" to deny service to all siblings.
CWE-20 - Improper Input Validation
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.