fix: unknown values in metrics cvedb

Author: Saksham-Sirohi

cve_bin_tool/cvedb.py

@@ -310,6 +310,14 @@ def refresh_cache_and_update_db(self) -> None:
         self.create_exploit_db()
         self.update_exploits()
 
+        # Check if metrics need to be updated
+        cursor = self.db_open_and_get_cursor()
+        if not self.latest_schema("metrics", self.TABLE_SCHEMAS["metrics"], cursor):
+            self.LOGGER.info("Updating metrics data.")
+            self.populate_metrics()
+            self.connection.commit()
+        self.db_close()
+
     def get_cvelist_if_stale(self) -> None:
         """Update if the local db is more than one day old.
         This avoids the full slow update with every execution.
@@ -370,7 +378,13 @@ def latest_schema(
         if table_schema == current_schema:
             schema_latest = True
 
-        # check for cve_
+        # Check for metrics table schema
+        if table_name == "metrics":
+            result = cursor.execute(
+                "SELECT * FROM metrics WHERE metrics_id=?", (UNKNOWN_METRIC_ID,)
+            )
+            if not result.fetchone():
+                schema_latest = False
 
         return schema_latest