Programs that manipulate binary files are common vectors for attacks. A malformed file can trick even well-written and well-tested parsers into executing code that they shouldn't, or corrupting aspects of the user's environment.

For example, cvedetails.com, some random website I found from Googling, lists 13 vulnerabilities for Photoshop and 31 for Libreoffice in the last few years.

There have been plenty of attacks targeting image and document viewers/editors over the years. It's a great vector, because recipients are more likely to open a document than run an executable.

Some of the very "best" vulnerabilities of all time have been attacks taking advantage of scripting features in Office.

https://www.securityfocus.com/bid/109374 just recently.