Vulnerability · Published Jul 27, 2026 · Assigned by CERT-PL
CVE-2026-16554Integer Overflow Leading to Heap Buffer Overflow in cJSON
Medium 5.1
In plain English
A medium-severity integer overflow in cJSON from DaveGamble. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 31% of all known vulnerabilities).
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | cjson | no fix listed | DEBIAN-CVE-2026-16554 |
| Debian:13 | cjson | no fix listed | DEBIAN-CVE-2026-16554 |
| Debian:14 | cjson | no fix listed | DEBIAN-CVE-2026-16554 |
| Ubuntu:26.04:LTS | cjson | no fix listed | UBUNTU-CVE-2026-16554 |
| Ubuntu:26.10 | cjson | no fix listed | UBUNTU-CVE-2026-16554 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| DaveGamble | cJSON | 1.7.19 |
Weakness: CWE-190 · Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:L/SI:L/SA:L