CVE-2026-29036

A vulnerability was found in DaveGamble cJSON up to 1.7.19. The affected element is the function cJSONUtils_MergePatch of the file cJSON_Utils.c. The manipulation results in use after free, and the attack may be launched remotely. The exploit has been made public and could be used, and the pull request to fix this issue awaits acceptance.

A vulnerability in the cJSON library (up to version 1.7.19) causes JSON Patch operations (RFC 6902) to be non-atomic – on validation failure, the target element is removed before full validation, allowing an attacker to modify the document despite an error being reported.

A vulnerability in the cJSON library (up to version 1.7.19) causes inefficient algorithmic complexity in cJSON_Compare(), which performs an exponential number of operations when comparing deeply nested objects, potentially leading to denial of service (DoS).

cJSON through 1.7.19 is vulnerable to uncontrolled recursion leading to stack exhaustion when applying untrusted RFC 6902 JSON Patch via cJSONUtils_ApplyPatches. An attacker can supply a patch with add and copy operations that amplify document depth, causing a stack overflow and process crash.

cJSON library is vulnerable to an integer overflow in the print_string_ptr() function in cJSON.c on 32-bit platforms. The escape_characters counter, a 32-bit size_t, can wrap around when processing strings containing approximately 858,993,460 or more control characters, causing the output buffer to be allocated based on an underestimated length. When cJSON_PrintBuffered() is used with a pre-allocated buffer, the subsequent write loop overflows the heap allocation. An attacker supplying a crafted JSON string to an application using cJSON on a 32-bit platform can cause a heap buffer overflow, potentially leading to remote code execution, information disclosure, or denial of service. Because project creator contact attempts were unsuccessful, the vulnerability has only been confirmed in version 1.7.19 but may also affect other versions.