PHP Out-of-bounds Write Vulnerability - CVE-2017-9226

An issue was discovered in Oniguruma 6.2.0 as used in Oniguruma-mod in Ruby through 2.4.1 and mbstring in PHP through 7.1.5. A heap out-of-bounds write or read occurs in next_state_val() during regular expression compilation. Octal numbers larger than 0xff are not handled correctly in fetch_token() and fetch_token_in_cc(). A malformed regular expression containing an octal number in the form of 3970039 would produce an invalid code point value larger than 0xff in next_state_val() resulting in an out-of-bounds write memory corruption.