Rangers have been hit with a UEFA charge but have avoided fresh sanctions over sectarian singing.
There had been speculation Rangers could face a third charge over sectarian chants this season but the fireworks issue is the only one listed on the charge sheet.
Some reports had claimed Rangers fans might have prompted fresh action over sectarian chants, leading to speculation over a potential stadium closure for their deciding group match against Young Boys on December 12 after 3,000-seat sections were closed off in two earlier games.
But the sole charge will be decided by UEFA's disciplinary panel on February 27 next year and will likely lead to a relatively minor fine.
Feyenoord have also been charged with setting off fireworks and blocking stairways.