diff --git a/fs_file/fields.py b/fs_file/fields.py
index 3dc2e8e4c6..62edebfe67 100644
--- a/fs_file/fields.py
+++ b/fs_file/fields.py
@@ -386,7 +386,7 @@ def convert_to_cache(self, value, record, validate=True):
                 # we come from an onchange
                 # The id is the third element of the url
                 att_id = value["url"].split("/")[3]
-                attachment = record.env["ir.attachment"].browse(int(att_id))
+                attachment = record.env["ir.attachment"].sudo().browse(int(att_id))
                 return self._convert_attachment_to_cache(attachment)
             return FSFileValue(
                 name=value["filename"], value=base64.b64decode(value["content"])
diff --git a/fs_file/readme/newsfragments/288.bugfix b/fs_file/readme/newsfragments/288.bugfix
new file mode 100644
index 0000000000..79e4bb3b50
--- /dev/null
+++ b/fs_file/readme/newsfragments/288.bugfix
@@ -0,0 +1,6 @@
+Browse attachment with sudo() to avoid read access errors
+
+In models that have a multi fs image relation, a new line
+in form will trigger onchanges and will call the fs.file model
+'convert_to_cache()' method that will try to browse the attachment
+with user profile that could have no read rights on attachment model.