Why are apostrophes appearing when generating a CSV?

There is an option Manage to handle Excel and CSV output that could be interpreted as a formula.

Once excel interprets a cell as active content, it will attempt to execute functions contained in it.

Example:

"-2+3+cmd|' /C calc'!A0" will open the calculator app on a user's PC.

The solution is to put an apostrophe before:

• +
• _
• @
• =

Additional information about Comma-separated values.