#399

backend/app/services/post_thumbnail_upload_validator.rb

@@ -11,8 +11,10 @@ class PostThumbnailUploadValidator
     end
     raise InvalidUpload, 'thumbnail file size が大きすぎます．' if thumbnail.size > MAX_THUMBNAIL_BYTES
     raise InvalidUpload, 'サムネイル画像の形式が不正です．' unless allowed_content_type?(thumbnail.content_type)
+    raise InvalidUpload, 'サムネイル画像の形式が不正です．' if Post.svg_document_bytes?(thumbnail.read)
+    thumbnail.rewind
 
-    attachment = Post.resized_thumbnail_attachment(thumbnail)
+    attachment = Post.resized_thumbnail_attachment(thumbnail, content_type: thumbnail.content_type)
     attachment[:io].close if attachment[:io].respond_to?(:close)
   rescue MiniMagick::Error
     raise InvalidUpload, 'サムネイル画像の変換に失敗しました．'

backend/app/services/preview/thumbnail_fetcher.rb

@@ -32,7 +32,7 @@ module Preview
     def self.fetch_image_response(raw_url)
       uri, = UrlSafety.validate(raw_url)
       response = HttpFetcher.fetch(uri.to_s)
-      unless allowed_remote_image_content_type?(response.content_type)
+      unless allowed_remote_image_content_type?(response.content_type) || Post.svg_document_bytes?(response.body)
         raise GenerationFailed, 'サムネール画像が見つかりませんでした．'
       end