CVE-2026-16554: 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 aroun
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.
Details
Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-16554
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Low exploitation riskCVE-2026-165540.25% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 16% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-16554 | coverage & exploitation status | NVD · CVE.org |
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