CVE-2019-17498

I just wanted to point out that libssh2 is vulnerable from CVE-2019-17498: https://nvd.nist.gov/vuln/detail/CVE-2019-17498.

Based on the website, libssh2/libssh2@dedcbd1 patches it, but is unfortunately unavailable in the latest stable version.

I was sent by #17 (comment).