--- /n/sources/plan9/sys/src/cmd/ssh2/netssh.c	Thu Apr 19 10:50:04 2012
+++ /sys/src/cmd/ssh2/netssh.c	Tue Sep 22 00:00:00 2026
@@ -2545,6 +2545,8 @@
 			qunlock(&c->l);
 			break;
 		case SSH_MSG_USERAUTH_SUCCESS:
+			if (c->role != Client)
+				bail(c, p, p2, "userauth success from a client");
 			establish(c);
 			break;
 		case SSH_MSG_USERAUTH_BANNER: