std::wstring ReadTextFile(const FilePath& filename) {
  wchar_t contents[64];
  std::wifstream file;
  file.open(filename.value().c_str());
  EXPECT_TRUE(file.is_open());
  file.getline(contents, arraysize(contents));
  file.close();
  return std::wstring(contents);
}

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.