389-ds-base: 389-ds-base: pre-authentication stack buffer overflow in get_ruvelement_from_berval() via unbounded replica id parsing

A stack buffer overflow flaw was found in 389 Directory Server (389-ds-base). The get_ruvelement_from_berval() function in repl5_ruv.c copies digit characters from a network-supplied RUV berval into a fixed 16-byte stack buffer without bounds checking. A remote unauthenticated attacker can crash the LDAP server by sending a crafted StartNSDS50ReplicationRequest extended operation containing a replica ID field with more than 16 digit characters. The overflow occurs during payload decoding, before any authorization check. Stack protectors limit impact to denial of service.