bool RequestParser::OnHeadersEnd() {
  bool matched = view_matcher_(request_->method(), request_->url().path(),
                               &stream_);

  if (!matched) {
    LOG_WARN("No view matches the request: %s %s", request_->method().c_str(),
             request_->url().path().c_str());
  }

  return matched;
}
The software 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 software 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.