curl: CVE-2023-23916: HTTP multi-header compression denial of service

Summary:

A server can send an HTTP response with many occurrences of Transfer-Encoding and/or Content-Encoding headers. Each listed encoding allocates a buffer. The number of encodings listed within each header is already bounded but the number of headers is not, allowing an HTTP response to consume all available memory.

Steps To Reproduce:

Using the curl test environment:

1. Extract test418 from the attached patch
2. runtests.pl 418

Supporting Material/References:

Patch fixing the problem and new test for the case.

Impact

Denial of service.