DaveGamble cJSON 1.7.19 cJSON.c print_string_ptr integer overflow

Summaryinfo

A vulnerability was found in DaveGamble cJSON 1.7.19. It has been rated as critical. This vulnerability affects the function print_string_ptr of the file cJSON.c. Performing a manipulation results in integer overflow. This vulnerability is reported as CVE-2026-16554. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability was found in DaveGamble cJSON 1.7.19. It has been classified as critical. This affects the function print_string_ptr of the file cJSON.c. The manipulation with an unknown input leads to a integer overflow vulnerability. CWE is classifying the issue as CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at cert.pl. This vulnerability is uniquely identified as CVE-2026-16554 since 07/22/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/27/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

• DaveGamble

Name

• cJSON

Version

• 1.7.19

CPE 2.3info

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CPE 2.2info

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