Short answer
Yes, this is an emergency. Raw dough can expand in your cat's stomach, causing a dangerous blockage or bloat. The yeast also ferments into alcohol, which is toxic to cats. Call your vet or the ASPCA Animal Poison Control Center at 888-426-4435 immediately.
Raw bread dough — Food safety facts
Do not feed · Cats · full breakdown on the linked food page
Emergency. Dough rises in the warm stomach, can cause life-threatening bloat, and the yeast ferments into alcohol — a small ball can cause alcohol poisoning.