fix: csv injection in annotations export (#29462)

Co-authored-by: hj24 <huangjian@dify.ai>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

api/core/helper/csv_sanitizer.py

@@ -0,0 +1,89 @@
+"""CSV sanitization utilities to prevent formula injection attacks."""
+
+from typing import Any
+
+
+class CSVSanitizer:
+    """
+    Sanitizer for CSV export to prevent formula injection attacks.
+
+    This class provides methods to sanitize data before CSV export by escaping
+    characters that could be interpreted as formulas by spreadsheet applications
+    (Excel, LibreOffice, Google Sheets).
+
+    Formula injection occurs when user-controlled data starting with special
+    characters (=, +, -, @, tab, carriage return) is exported to CSV and opened
+    in a spreadsheet application, potentially executing malicious commands.
+    """
+
+    # Characters that can start a formula in Excel/LibreOffice/Google Sheets
+    FORMULA_CHARS = frozenset({"=", "+", "-", "@", "\t", "\r"})
+
+    @classmethod
+    def sanitize_value(cls, value: Any) -> str:
+        """
+        Sanitize a value for safe CSV export.
+
+        Prefixes formula-initiating characters with a single quote to prevent
+        Excel/LibreOffice/Google Sheets from treating them as formulas.
+
+        Args:
+            value: The value to sanitize (will be converted to string)
+
+        Returns:
+            Sanitized string safe for CSV export
+
+        Examples:
+            >>> CSVSanitizer.sanitize_value("=1+1")
+            "'=1+1"
+            >>> CSVSanitizer.sanitize_value("Hello World")
+            "Hello World"
+            >>> CSVSanitizer.sanitize_value(None)
+            ""
+        """
+        if value is None:
+            return ""
+
+        # Convert to string
+        str_value = str(value)
+
+        # If empty, return as is
+        if not str_value:
+            return ""
+
+        # Check if first character is a formula initiator
+        if str_value[0] in cls.FORMULA_CHARS:
+            # Prefix with single quote to escape
+            return f"'{str_value}"
+
+        return str_value
+
+    @classmethod
+    def sanitize_dict(cls, data: dict[str, Any], fields_to_sanitize: list[str] | None = None) -> dict[str, Any]:
+        """
+        Sanitize specified fields in a dictionary.
+
+        Args:
+            data: Dictionary containing data to sanitize
+            fields_to_sanitize: List of field names to sanitize.
+                               If None, sanitizes all string fields.
+
+        Returns:
+            Dictionary with sanitized values (creates a shallow copy)
+
+        Examples:
+            >>> data = {"question": "=1+1", "answer": "+calc", "id": "123"}
+            >>> CSVSanitizer.sanitize_dict(data, ["question", "answer"])
+            {"question": "'=1+1", "answer": "'+calc", "id": "123"}
+        """
+        sanitized = data.copy()
+
+        if fields_to_sanitize is None:
+            # Sanitize all string fields
+            fields_to_sanitize = [k for k, v in data.items() if isinstance(v, str)]
+
+        for field in fields_to_sanitize:
+            if field in sanitized:
+                sanitized[field] = cls.sanitize_value(sanitized[field])
+
+        return sanitized