===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/ssh/auth-options.c,v
retrieving revision 1.78
retrieving revision 1.79
diff -u -r1.78 -r1.79
--- src/usr.bin/ssh/auth-options.c	2018/03/14 05:35:40	1.78
+++ src/usr.bin/ssh/auth-options.c	2018/04/06 04:15:45	1.79
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth-options.c,v 1.78 2018/03/14 05:35:40 djm Exp $ */
+/* $OpenBSD: auth-options.c,v 1.79 2018/04/06 04:15:45 djm Exp $ */
 /*
  * Copyright (c) 2018 Damien Miller <djm@mindrot.org>
  *
@@ -391,7 +391,7 @@
 				goto fail;
 			}
 			for (cp = opt; cp < tmp; cp++) {
-				if (!isalnum((u_char)*cp)) {
+				if (!isalnum((u_char)*cp) && *cp != '_') {
 					free(opt);
 					errstr = "invalid environment string";
 					goto fail;