untrusted comment: signature from openbsd 6.0 base secret key
RWSho3oKSqgLQxiq51WTIK3qrNKc5AWhXdPYQuvyLDUcT1XyY0eMjaeMElPHQNTmLhh71i2s2ioVSx7VX+y78HVn9KT09SJItA4=

OpenBSD 6.0 errata 022, May 7, 2017:

Incorrect DTLS cookie handling can result in a NULL pointer dereference.

Apply by doing:
   signify -Vep /etc/signify/openbsd-60-base.pub -x 022_libssl.patch.sig \
       -m - | (cd /usr/src && patch -p0)

And then rebuild and install libssl:
       cd /usr/src/lib/libssl/ssl
       make obj
       make depend
       make
       make install

Index: lib/libssl/src/ssl/s3_srvr.c
===================================================================
RCS file: /cvs/src/lib/libssl/src/ssl/Attic/s3_srvr.c,v
retrieving revision 1.126.2.1
retrieving revision 1.126.2.2
diff -u -p -r1.126.2.1 -r1.126.2.2
--- lib/libssl/src/ssl/s3_srvr.c        3 Oct 2016 11:23:13 -0000       1.126.2.1
+++ lib/libssl/src/ssl/s3_srvr.c        30 Apr 2017 00:06:09 -0000      1.126.2.2
@@ -721,7 +721,7 @@ ssl3_send_hello_request(SSL *s)
int
ssl3_get_client_hello(SSL *s)
{
-       int i, j, ok, al, ret = -1;
+       int i, j, ok, al, ret = -1, cookie_valid = 0;
       unsigned int cookie_len;
       long n;
       unsigned long id;
@@ -887,7 +887,7 @@ ssl3_get_client_hello(SSL *s)
                               goto f_err;
                       }

-                       ret = 2;
+                       cookie_valid = 1;
               }

               p += cookie_len;
@@ -1070,8 +1070,8 @@ ssl3_get_client_hello(SSL *s)
               goto err;
       }

-       if (ret < 0)
-               ret = 1;
+       ret = cookie_valid ? 2 : 1;
+
       if (0) {
truncated:
               al = SSL_AD_DECODE_ERROR;