# CVE-2026-16554: Integer Overflow Leading to Heap Buffer Overflow in cJSON

> Integer overflow in cJSON on 32-bit platforms allows heap buffer overflow via crafted JSON, potentially leading to remote code execution or denial of service.

- **Severity:** Medium 5.1 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 Jul 2026
- **Updated:** 31 Jul 2026
- **Also known as:** AZL-94184, AZL-94244, DEBIAN-CVE-2026-16554, GHSA-qv6q-8g2j-w47g, ROOT-OS-ALPINE-321-CVE-2026-16554, ROOT-OS-ALPINE-323-CVE-2026-16554, UBUNTU-CVE-2026-16554

## What is CVE-2026-16554?

CVE-2026-16554 is a medium-severity vulnerability in DaveGamble cJSON, published on 27 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### 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.

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2026-16554?

It affects 1 product.


Products: Davegamble Cjson.

## How do I fix CVE-2026-16554?

No fix published yet.

## Is CVE-2026-16554 being exploited?

There is no known exploitation of CVE-2026-16554 in the wild and no public exploit code.

## Other vulnerabilities in DaveGamble cJSON

- [CVE-2025-57052](https://insights.sbomify.com/CVE-2025-57052/): Memory corruption in n/a (critical 9.8)
- [CVE-2019-11834](https://insights.sbomify.com/CVE-2019-11834/): Memory corruption in n/a (critical 9.8)
- [CVE-2019-11835](https://insights.sbomify.com/CVE-2019-11835/): Memory corruption in n/a (critical 9.8)
- [CVE-2016-10749](https://insights.sbomify.com/CVE-2016-10749/): Memory corruption in n/a (critical 9.8)
- [CVE-2018-1000217](https://insights.sbomify.com/CVE-2018-1000217/): Use after free in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-16554 and fix it if it is affected.

What it is: CVE-2026-16554 is a medium-severity vulnerability in DaveGamble cJSON, published on 27 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-16554 in the wild and no public exploit code.

Affected product: DaveGamble cJSON. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-16554/ (Markdown: https://insights.sbomify.com/CVE-2026-16554/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-16554
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-16554
- OSV: https://osv.dev/vulnerability/CVE-2026-16554

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-16554/
Summaries are generated and may contain mistakes; the official description above is the record.