We caught a memory leak in SPNEGO.  This fixed it for us:

Index: src/lib/gssapi/spnego/spnego_mech.c
===================================================================
--- src/lib/gssapi/spnego/spnego_mech.c	(revision 23762)
+++ src/lib/gssapi/spnego/spnego_mech.c	(working copy)
@@ -1739,9 +1739,12 @@
 	}
 	if (ret == GSS_S_COMPLETE) {
 		*context_handle = (gss_ctx_id_t)sc->ctx_handle;
-		if (sc->internal_name != GSS_C_NO_NAME &&
-		    src_name != NULL) {
+		if (sc->internal_name != GSS_C_NO_NAME) {
+                    if (src_name != NULL) {
 			*src_name = sc->internal_name;
+                    } else {
+                        gss_release_name(&tmpmin, &sc->internal_name);
+                    }
 		}
 		release_spnego_ctx(&sc);
 	} else if (ret != GSS_S_CONTINUE_NEEDED) {