33 Vulnerabilities in cJSON

cJSON is probably the most widely used JSON parser in the C world. It’s vendored into ESP-IDF, into a lot of embedded firmware, and into a whole lot more server-side C. I found 33 security issues in it, using a mix of AI and some manual fuzzing and review. They affect every version up to and including v1.7.19, and every one of them is still in the current code.