Atril Document Viewer is the default document reader of the MATE desktop environment for Linux. A path traversal and arbitrary file write vulnerability exists in versions of Atril prior to 1.26.2. This vulnerability is capable of writing arbitrary files anywhere on the filesystem to which the user opening a crafted document has access. The only limitation is that this vulnerability cannot be exploited to overwrite existing files, but that doesn't stop an attacker from achieving Remote Command Execution on the target system. Version 1.26.2 of Atril contains a patch for this vulnerability.
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.