As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT 23,000 FEET STARTED TO FEEL CABIN RISING AND GOT THE ALT HORN. CABIN WAS AT 11,000 FEET AND CLIMBING 1000 FPM. STARTED DESCENT AUTO SYS FAILED TO STBY BUT CABIN KEPT CLIMBING UNTIL A/C PASSED THROUGH ACTUAL ALTITUDE. REPLACED PRESSURE CONTROLLER AND AFT OUTFLOW VALVE PER MM.