Affected: JSON-XS

JSON::XS versions from 4.0_00 before 4.05 for Perl corrupt the incremental buffer length by chopping past its end in incr_skip after a top-level number.

The incremental parser scans any run of digits, signs, dots and exponent markers as one number, but the decoder stops at the end of a valid number, so the parser keeps an offset into bytes it has not decoded. It then empties the buffer without clearing those bytes, and a later incr_parse call without new input reads them again and moves the offset past the end of the buffer. incr_skip, the documented recovery after an error, removes that many bytes and the buffer length wraps.

A peer sending input such as "1-2" to an incr_parse consumer can make the next read of incr_text exit the process through perl's uncatchable out-of-memory path.