untrusted comment: signature from openbsd 5.7 base secret key
RWSvUZXnw9gUb7LsFgSrQ2cEEMLLd5O+80Cq0cAPVVKWxX+D8JdSRVKs/Vg4KOCUdPQ2smJZwK/ESOvPxY90Yiw1gpElQgHNQgk=

OpenBSD 5.7 errata 5, Apr 30, 2015:

Logging to a log file is only possible after the logging system was
initialized. Trying to log too early allows a remote user to crash
httpd.

Apply by doing:
   cd /usr/src
   signify -Vep /etc/signify/openbsd-57-base.pub -x 005_httpd.patch.sig -m - | \
       patch -p0

And then rebuild and install httpd:
   cd usr.sbin/httpd
   make obj
   make
   make install

Index: usr.sbin/httpd/server.c
===================================================================
RCS file: /cvs/src/usr.sbin/httpd/server.c,v
retrieving revision 1.60
diff -u -p -r1.60 server.c
--- usr.sbin/httpd/server.c     23 Feb 2015 09:52:28 -0000      1.60
+++ usr.sbin/httpd/server.c     23 Apr 2015 17:32:46 -0000
@@ -851,6 +851,11 @@ server_accept(int fd, short event, void
       if ((clt = calloc(1, sizeof(*clt))) == NULL)
               goto err;

+       /* Pre-allocate log buffer */
+       clt->clt_log = evbuffer_new();
+       if (clt->clt_log == NULL)
+               goto err;
+
       clt->clt_s = s;
       clt->clt_fd = -1;
       clt->clt_toread = TOREAD_UNLIMITED;
@@ -895,13 +900,6 @@ server_accept(int fd, short event, void
       clt->clt_output = evbuffer_new();
       if (clt->clt_output == NULL) {
               server_close(clt, "failed to allocate output buffer");
-               return;
-       }
-
-       /* Pre-allocate log buffer */
-       clt->clt_log = evbuffer_new();
-       if (clt->clt_log == NULL) {
-               server_close(clt, "failed to allocate log buffer");
               return;
       }