diff --git a/runtime/repair-webdav-cache-permissions.sh b/runtime/repair-webdav-cache-permissions.sh
new file mode 100644
index 0000000..92bf21f
--- /dev/null
+++ b/runtime/repair-webdav-cache-permissions.sh
@@ -0,0 +1,36 @@
+#!/usr/bin/env bash
+set -Eeuo pipefail
+
+PIWIGO_ROOT="${1:-/var/www/piwigo}"
+PIWIGO_ROOT="${PIWIGO_ROOT%/}"
+DATA_DIR="$PIWIGO_ROOT/_data"
+
+[[ -d "$DATA_DIR" ]] || { echo "Piwigo-_data wurde nicht gefunden: $DATA_DIR" >&2; exit 1; }
+[[ "$(id -u)" -eq 0 ]] || { echo "Die Reparatur muss als root ausgeführt werden." >&2; exit 1; }
+
+DATA_UID="$(stat -c '%u' "$DATA_DIR")"
+DATA_GID="$(stat -c '%g' "$DATA_DIR")"
+
+PATHS=(
+  "$DATA_DIR/bratonien-tools/nc-webdav-gallery"
+  "$DATA_DIR/bratonien-tools/nc-webdav-preview"
+  "$DATA_DIR/i/_data/bratonien-tools/nc-webdav-gallery"
+  "$DATA_DIR/i/bratonien-watermark"
+)
+
+found=0
+for path in "${PATHS[@]}"; do
+  [[ -e "$path" ]] || continue
+  found=1
+  echo "Repariere: $path"
+  chown -R "$DATA_UID:$DATA_GID" -- "$path"
+  find "$path" -type d -exec chmod 2775 {} +
+  find "$path" -type f -exec chmod 0664 {} +
+done
+
+if [[ "$found" -eq 0 ]]; then
+  echo "Keine Bratonien-Cache-Verzeichnisse gefunden."
+  exit 0
+fi
+
+echo "Bratonien-Cache-Rechte wurden an $DATA_DIR angeglichen (UID $DATA_UID, GID $DATA_GID)."