Integer overflow (wraparound) vulnerability in Corosync’s join message sanity validation in exec/totemsrp.c. The flaw is in check_memb_join_sanity(), where proc_list_entries and failed_list_entries are attacker-controlled 32-bit unsigned values received from the network and are added together before being promoted to size_t. This allows the addition (proc_list_entries + failed_list_entries) to wrap around in 32-bit arithmetic (e.g., 0x80000000 + 0x80000000 = 0), causing required_len to be calculated too small and allowing a short packet to pass validation. As a result, Corosync proceeds with processing malformed input that should have been rejected, which can be exploited remotely without authentication in totemudp/totemudpu mode via crafted UDP packets to crash the service, resulting in a denial of service.