Impala and Hive's unescaping of octal escape sequences is flawed.

Impala reuses Hive's code to do deal with escape sequences, so both Hive and Impala are affected.

Octal values > 127 fail to unescape properly. This may lead to problems if, e.g., a user has text data with exotic single-byte delimiters (UTF-8 single byte or ASCII extended).

For example,

select "\127" returns "W
but
select "\128" returns "128"