OpenConnect through 8.08 mishandles negative return values from X509_check_ function calls, which might assist attackers in performing man-in-the-middle attacks.
https://security.gentoo.org/glsa/202006-15
https://gitlab.com/openconnect/openconnect/-/merge_requests/96
http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00039.html