Directory traversal vulnerability in EspoCRM before 2.6.0 allows remote attackers to include and execute arbitrary local files via a .. (dot dot) in the action parameter to install/index.php.
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.