untrusted comment: verify with openbsd-68-base.pub
RWQZj25CSG5R2lgsgSLgQjjy3/BFahe7C64NJOej05Naf0mm//TKykuXL7pxOVsY5rnXH0A6vBdO5UNx7PkuTxLOACHx5xV7Gws=

OpenBSD 6.8 errata 015, March 4, 2021:

Double free in ssh-agent(1)

Apply by doing:
   signify -Vep /etc/signify/openbsd-68-base.pub -x 015_sshagent.patch.sig \
       -m - | (cd /usr/src && patch -p0)

And then rebuild and install ssh (as well as ssh-agent)
   cd /usr/src/usr.bin/ssh
   make obj
   make clean
   make
   make install

Index: usr.bin/ssh/ssh-agent.c
===================================================================
RCS file: /cvs/src/usr.bin/ssh/ssh-agent.c,v
diff -u -p -u -r1.264 ssh-agent.c
--- usr.bin/ssh/ssh-agent.c     18 Sep 2020 08:16:38 -0000      1.264
+++ usr.bin/ssh/ssh-agent.c     3 Mar 2021 01:08:25 -0000
@@ -567,6 +567,7 @@ process_add_identity(SocketEntry *e)
                               goto err;
                       }
                       free(ext_name);
+                       ext_name = NULL;
                       break;
               default:
                       error("%s: Unknown constraint %d", __func__, ctype);