diff --git a/cli/class-tmdo-cli.php b/cli/class-tmdo-cli.php
index c32b9a4..a8ae9fb 100644
--- a/cli/class-tmdo-cli.php
+++ b/cli/class-tmdo-cli.php
@@ -162,6 +162,7 @@ class TMDO_CLI {
 			// v2.1.2 doctor column-drift check: compare DB columns vs Schema_Registry declared columns.
 			$declared = array_keys( $registry->get_hot_columns( $pt ) );
 			$existing = array();
+			self::assert_safe_table_name( $t );
 			if ( TMDO_IS_MYSQL ) {
 				// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching,WordPress.DB.PreparedSQL.InterpolatedNotPrepared,WordPress.DB.PreparedSQL.NotPrepared
 				$rows     = $wpdb->get_col( "SHOW COLUMNS FROM `{$t}`" );
@@ -914,6 +915,7 @@ class TMDO_CLI {
 				continue;
 			}
 
+			self::assert_safe_table_name( $full_table );
 			$total_rows = (int) $wpdb->get_var( "SELECT COUNT(*) FROM `{$full_table}`" ); // phpcs:ignore WordPress.DB
 
 			// Use partner-supplied callback when available.
@@ -1318,6 +1320,22 @@ class TMDO_CLI {
 
 	// ── Private helpers ───────────────────────────────────────────────────
 
+	/**
+	 * Reject table names that are not plain identifiers.
+	 *
+	 * Guards raw SQL that cannot use $wpdb->prepare() for table identifiers
+	 * (SHOW COLUMNS, PRAGMA, COUNT(*) probes). All callers derive $table_name
+	 * from TMDO_DB::table() or Custom_Table_Registry — developer-controlled,
+	 * not from HTTP input — but this check prevents breakage if that ever changes.
+	 *
+	 * @param string $table_name Fully-qualified table name to validate.
+	 */
+	private static function assert_safe_table_name( string $table_name ): void {
+		if ( ! preg_match( '/^[a-zA-Z0-9_]+$/', $table_name ) ) {
+			WP_CLI::error( "Unsafe table name rejected: '{$table_name}'" );
+		}
+	}
+
 	/**
 	 * Format the HPCT status string for display.
 	 *
diff --git a/includes/class-tmdo-installer.php b/includes/class-tmdo-installer.php
index fd434f4..12353b7 100644
--- a/includes/class-tmdo-installer.php
+++ b/includes/class-tmdo-installer.php
@@ -38,6 +38,48 @@ class TMDO_Installer {
 	 */
 	private const SCHEMA_VERSION = '2.1.0';
 
+	/** Allowed SQL base types for hot-zone column definitions. */
+	private const ALLOWED_COL_BASE_TYPES = array(
+		'bigint',
+		'int',
+		'tinyint',
+		'smallint',
+		'mediumint',
+		'decimal',
+		'float',
+		'double',
+		'varchar',
+		'char',
+		'text',
+		'longtext',
+		'mediumtext',
+		'datetime',
+		'date',
+		'timestamp',
+		'json',
+	);
+
+	/**
+	 * Assert that a column type string starts with an allowed SQL base type.
+	 *
+	 * Prevents rogue partner plugins from injecting arbitrary DDL via Schema Registry.
+	 *
+	 * @param string $col_type Full column definition, e.g. "DECIMAL(10,2) NOT NULL DEFAULT '0'".
+	 * @param string $col_name Column name (for error context).
+	 * @throws \InvalidArgumentException When the base type is not in the allowlist.
+	 */
+	private static function validate_col_type( string $col_type, string $col_name ): void {
+		$base = strtolower( strtok( trim( $col_type ), " \t(" ) );
+		if ( ! in_array( $base, self::ALLOWED_COL_BASE_TYPES, true ) ) {
+			// phpcs:disable WordPress.Security.EscapeOutput.ExceptionNotEscaped -- internal exception, never rendered to HTML.
+			throw new \InvalidArgumentException(
+				"TMDO_Installer: disallowed column type '{$base}' for column '{$col_name}'. " .
+				'Allowed: ' . implode( ', ', self::ALLOWED_COL_BASE_TYPES )
+			);
+			// phpcs:enable WordPress.Security.EscapeOutput.ExceptionNotEscaped
+		}
+	}
+
 	// ── Public API ────────────────────────────────────────────────────────
 
 	/**
@@ -958,6 +1000,7 @@ class TMDO_Installer {
 			if ( method_exists( $wpdb, 'hide_errors' ) ) {
 				$wpdb->hide_errors();
 			}
+			self::validate_col_type( $col_type, $safe_name );
 			// phpcs:ignore WordPress.DB.DirectDatabaseQuery,WordPress.DB.DirectDatabaseQuery.NoCaching,WordPress.DB.PreparedSQL.InterpolatedNotPrepared,WordPress.DB.PreparedSQL.NotPrepared
 			$ok = $wpdb->query( "ALTER TABLE `{$table}` ADD COLUMN `{$safe_name}` {$col_type}" );
 			if ( $prev_show && method_exists( $wpdb, 'show_errors' ) ) {
@@ -1032,6 +1075,7 @@ class TMDO_Installer {
 
 		foreach ( $columns as $col_name => $col_type ) {
 			$safe_name = sanitize_key( $col_name );
+			self::validate_col_type( $col_type, $safe_name );
 			$col_defs .= "  {$safe_name} {$col_type},\n";
 
 			$base_type     = strtolower( strtok( $col_type, '(' ) );