parse_string in cJSON.c in cJSON before 2016-10-02 has a buffer over-read, as demonstrated by a string that begins with a " character and ends with a \ character.
https://www.openwall.com/lists/oss-security/2016/11/07/2
https://github.com/DaveGamble/cJSON/issues/30
https://github.com/DaveGamble/cJSON/commit/94df772485c92866ca417d92137747b2e3b0a917