OpenConnect 8.09 has a buffer overflow, causing a denial of service (application crash) or possibly unspecified other impact, via crafted certificate data to getcertname in gnutls.c.

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

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

OpenConnect before 2.25 does not properly validate X.509 certificates, which allows man-in-the-middle attackers to spoof arbitrary AnyConnect SSL VPN servers via a crafted server certificate that (1) does not correspond to the server hostname or (2) is presented in circumstances involving a missing --cafile configuration option.

OpenConnect through 8.08 mishandles negative return values from X509check function calls, which might assist attackers in performing man-in-the-middle attacks.

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.

OpenConnect before 2.26 places the webvpn cookie value in the debugging output, which might allow remote attackers to obtain sensitive information by reading this output, as demonstrated by output posted to the public openconnect-devel mailing list.

Unspecified vulnerability in OpenConnect before 2.23 allows remote AnyConnect SSL VPN servers to cause a denial of service (application crash) via a 404 HTTP status code.

Double free vulnerability in OpenConnect before 1.40 might allow remote AnyConnect SSL VPN servers to cause a denial of service (application crash) or possibly have unspecified other impact via a crafted DTLS Cipher option during a reconnect operation.