Full Report
Integer overflow vulnerability (CVE-2026-16554) has been found in DaveGamble cJSON library.
Analysis Summary
# Vulnerability: Integer Overflow in DaveGamble cJSON Library
## CVE Details
- **CVE ID**: CVE-2026-16554
- **CVSS Score**: Not specifically provided in the source (Estimate: High/Critical due to potential RCE)
- **CWE**: CWE-190 (Integer Overflow or Wraparound)
## Affected Systems
- **Products**: DaveGamble cJSON library
- **Versions**: 1.7.19 confirmed; other versions may be affected.
- **Configurations**: Applications running on **32-bit platforms** that use the library to process large or crafted JSON strings.
## Vulnerability Description
An integer overflow exists in the `print_string_ptr()` function within `cJSON.c`. The vulnerability occurs because the `escape_characters` counter (a 32-bit `size_t` on affected platforms) can wrap around when processing strings containing a massive number of control characters (approximately 858,993,460 or more).
When the counter wraps around, the application calculates an underestimated length for the output buffer. Consequently, when `cJSON_PrintBuffered()` is called with a pre-allocated buffer, the subsequent write loop results in a heap buffer overflow.
## Exploitation
- **Status**: Reported/Disclosed (PoC status not explicitly stated, but technical trigger mechanism is identified).
- **Complexity**: Medium (Requires the ability to pass a very large, specific string to the library).
- **Attack Vector**: Network (Remote if the application processes external JSON input).
## Impact
- **Confidentiality**: High (Potential for information disclosure).
- **Integrity**: High (Potential for Remote Code Execution (RCE)).
- **Availability**: High (Potential for Denial of Service (DoS) via heap corruption).
## Remediation
### Patches
- **Status**: No official patch currenty available.
- **Notes**: Attempts to contact the vendor (DaveGamble) have been unsuccessful as of the publication date (July 27, 2026).
### Workarounds
- **Architecture Migration**: Use 64-bit platforms where `size_t` is 64-bit, making the overflow computationally impractical.
- **Input Validation**: Implement strict limits on the size of JSON input and the number of control characters allowed in strings before they are passed to cJSON functions.
- **Buffer Management**: Avoid using `cJSON_PrintBuffered()` with untrusted input on 32-bit systems if the input length cannot be verified.
## Detection
- **Indicators of Compromise**: Unexpected application crashes (SIGSEGV) in 32-bit environments during JSON serialization.
- **Detection Methods**: Static analysis of source code focusing on `cJSON.c:print_string_ptr()`. Monitoring for unusually large JSON payloads (approaching or exceeding 800MB) directed at 32-bit services.
## References
- CERT Polska Advisory: hxxps[://]cert[.]pl/en/posts/2026/07/CVE-2026-16554/
- CVE Record: hxxps[://]www[.]cve[.]org/CVERecord?id=CVE-2026-16554
- CWE-190 Definition: hxxps[://]cwe[.]mitre[.]org/data/definitions/190[.]html