CVE-2026-16554: medium-severity vulnerability in DaveGamble cJSON
Integer Overflow Leading to Heap Buffer Overflow in cJSON
Published · Updated
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13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.1epss 0.4%
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.
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
Affected products
DaveGamble · cJSONRelated CVEs — DaveGamble cJSON
In the same product, most dangerous first.
CVE-2026-67215HIGHcJSON JSON Patch copy/add Uncontrolled Recursion Stack ExhaustionEPSS 0.7%CVE-2026-67216HIGHcJSON cJSON_Compare Exponential Complexity Denial of ServiceEPSS 0.6%CVE-2026-87933MEDIUMDaveGamble cJSON cJSON_Utils.c cJSONUtils_MergePatch use after freeEPSS 0.5%CVE-2026-29036HIGHcJSON 1.7.19 Wrong-Key Modification via JSON Pointer Escape DecodingEPSS 0.4%CVE-2026-67217MEDIUMcJSON JSON Patch Non-Atomic Application Destroys Data Before ValidationEPSS 0.4%