diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 83f35ecacf24..2d68a173b227 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -1743,7 +1743,7 @@ static void copy_templates(struct xfrm_policy *xp, struct xfrm_user_tmpl *ut,
 }
 
 static int validate_tmpl(int nr, struct xfrm_user_tmpl *ut, u16 family,
-			 struct netlink_ext_ack *extack)
+			 int dir, struct netlink_ext_ack *extack)
 {
 	u16 prev_family;
 	int i;
@@ -1769,6 +1769,10 @@ static int validate_tmpl(int nr, struct xfrm_user_tmpl *ut, u16 family,
 		switch (ut[i].mode) {
 		case XFRM_MODE_TUNNEL:
 		case XFRM_MODE_BEET:
+			if (ut[i].optional && dir == XFRM_POLICY_OUT) {
+				NL_SET_ERR_MSG(extack, "Mode in optional template not allowed in outbound policy");
+				return -EINVAL;
+			}
 			break;
 		default:
 			if (ut[i].family != prev_family) {
@@ -1806,7 +1810,7 @@ static int validate_tmpl(int nr, struct xfrm_user_tmpl *ut, u16 family,
 }
 
 static int copy_from_user_tmpl(struct xfrm_policy *pol, struct nlattr **attrs,
-			       struct netlink_ext_ack *extack)
+			       int dir, struct netlink_ext_ack *extack)
 {
 	struct nlattr *rt = attrs[XFRMA_TMPL];
 
@@ -1817,7 +1821,7 @@ static int copy_from_user_tmpl(struct xfrm_policy *pol, struct nlattr **attrs,
 		int nr = nla_len(rt) / sizeof(*utmpl);
 		int err;
 
-		err = validate_tmpl(nr, utmpl, pol->family, extack);
+		err = validate_tmpl(nr, utmpl, pol->family, dir, extack);
 		if (err)
 			return err;
 
@@ -1894,7 +1898,7 @@ static struct xfrm_policy *xfrm_policy_construct(struct net *net,
 	if (err)
 		goto error;
 
-	if (!(err = copy_from_user_tmpl(xp, attrs, extack)))
+	if (!(err = copy_from_user_tmpl(xp, attrs, p->dir, extack)))
 		err = copy_from_user_sec_ctx(xp, attrs);
 	if (err)
 		goto error;
@@ -3443,7 +3447,7 @@ static struct xfrm_policy *xfrm_compile_policy(struct sock *sk, int opt,
 		return NULL;
 
 	nr = ((len - sizeof(*p)) / sizeof(*ut));
-	if (validate_tmpl(nr, ut, p->sel.family, NULL))
+	if (validate_tmpl(nr, ut, p->sel.family, p->dir, NULL))
 		return NULL;
 
 	if (p->dir > XFRM_POLICY_OUT)