diff --git a/isisd/isis_tlvs.c b/isisd/isis_tlvs.c
index d573d4044e..9fc602c209 100644
--- a/isisd/isis_tlvs.c
+++ b/isisd/isis_tlvs.c
@@ -135,6 +135,9 @@ struct isis_ext_subtlvs *isis_alloc_ext_subtlvs(void)
 	init_item_list(&ext->lan_sid);
 	ext->aslas = list_new();
 
+	init_item_list(&ext->srv6_endx_sid);
+	init_item_list(&ext->srv6_lan_endx_sid);
+
 	admin_group_init(&ext->ext_admin_group);
 
 	return ext;
@@ -166,6 +169,18 @@ void isis_del_ext_subtlvs(struct isis_ext_subtlvs *ext)
 
 	admin_group_term(&ext->ext_admin_group);
 
+	/* First, free SRv6 End.X SID and SRv6 LAN End.X SID list if needed */
+	for (item = ext->srv6_endx_sid.head; item; item = next_item) {
+		next_item = item->next;
+		isis_free_subsubtlvs(((struct isis_srv6_endx_sid_subtlv *)item)->subsubtlvs);
+		XFREE(MTYPE_ISIS_SUBTLV, item);
+	}
+	for (item = ext->srv6_lan_endx_sid.head; item; item = next_item) {
+		next_item = item->next;
+		isis_free_subsubtlvs(((struct isis_srv6_lan_endx_sid_subtlv *)item)->subsubtlvs);
+		XFREE(MTYPE_ISIS_SUBTLV, item);
+	}
+
 	XFREE(MTYPE_ISIS_SUBTLV, ext);
 }
 
diff --git a/isisd/isis_tlvs.h b/isisd/isis_tlvs.h
index 1b48fd579a..138e5bbeae 100644
--- a/isisd/isis_tlvs.h
+++ b/isisd/isis_tlvs.h
@@ -639,6 +639,8 @@ enum ext_subsubtlv_types {
 #define EXT_AVA_BW		0x080000
 #define EXT_USE_BW		0x100000
 #define EXT_EXTEND_ADM_GRP 0x200000
+#define EXT_SRV6_ENDX_SID 0x400000
+#define EXT_SRV6_LAN_ENDX_SID 0x800000
 
 /*
  * This structure groups all Extended IS Reachability subTLVs.
@@ -688,6 +690,10 @@ struct isis_ext_subtlvs {
 	struct isis_item_list lan_sid;
 
 	struct list *aslas;
+
+	/* SRv6 End.X & LAN End.X SID */
+	struct isis_item_list srv6_endx_sid;
+	struct isis_item_list srv6_lan_endx_sid;
 };
 
 /* RFC 8919 */