Peaches (pitted) — Food safety facts
Feed with care · Cats · full breakdown on the linked food page
Small flesh pieces are safe. The pit contains cyanide compounds and can cause blockage.
Short answer
No, a tiny taste of peach flesh from a properly pitted slice is not dangerous for your cat. The flesh itself is safe in small amounts, but the pit is a serious hazard as it contains cyanide compounds and can cause an intestinal blockage if swallowed. Always ensure the peach is thoroughly pitted before offering any, and watch for vomiting or lethargy which would warrant a vet visit.