OpenConnect through 8.08 mishandles negative return values from X509_check_ function calls, which might assist attackers in performing man-in-the-middle attacks.

OpenConnect VPN client with GnuTLS before 5.02 contains a heap overflow if MTU is increased on reconnection.

process_http_response in OpenConnect before 8.05 has a Buffer Overflow when a malicious server uses HTTP chunked encoding with crafted chunk sizes.

Multiple stack-based buffer overflows in http.c in OpenConnect before 4.08 allow remote VPN gateways to cause a denial of service (application crash) via a long (1) hostname, (2) path, or (3) cookie list in a response.

Heap-based buffer overflow in OpenConnect 3.18 allows remote servers to cause a denial of service via a crafted greeting banner.