CVE-2026-16554

cJSON library is vulnerable to an integer overflow in the printstringptr() function in cJSON.c on 32-bit platforms. The escapecharacters counter, a 32-bit sizet, 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.

Database specific

{
    "cna_assigner": "CERT-PL",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/16xxx/CVE-2026-16554.json",
    "cwe_ids": [
        "CWE-190"
    ]
}

References

Affected packages

Git / github.com/davegamble/cjson

Affected ranges

Type

GIT

Repo

https://github.com/davegamble/cjson

Events

Introduced

c859b25da02955fef659d658b8f324b5cde87be3

Last affected

c859b25da02955fef659d658b8f324b5cde87be3

Database specific

{
    "extracted_events": [
        {
            "introduced": "1.7.19"
        },
        {
            "last_affected": "1.7.19"
        }
    ],
    "source": "AFFECTED_FIELD"
}

Affected versions

1.*

1.7.19

v1.*

v1.7.19

Database specific

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-16554.json"