---
title: "CVE-2026-16554\n    | Ubuntu"
description: Ubuntu is an open source software operating system that runs from the
  desktop, to the cloud, to all your internet connected things.
url: https://ubuntu.com/security/CVE-2026-16554?format=md
keywords: index, follow
---

# CVE-2026-16554

Publication date 27 July 2026

Last updated 31 August 2026

---

Ubuntu priority

**Medium**

[Why this priority?](https://ubuntu.com/security/cves/about#priority )

## Cvss 3 Severity Score

**7.8 · High**

[Score breakdown](https://ubuntu.com/security/CVE-2026-16554?format=md#impact-score)

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## 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.

[Read the notes from the security team](https://ubuntu.com/security/CVE-2026-16554?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| cjson | 26.04 LTS resolute | Vulnerable, fix deferred |
| 24.04 LTS noble | Vulnerable, fix deferred |
| 22.04 LTS jammy | Vulnerable, fix deferred |
| 20.04 LTS focal | Vulnerable, fix deferred |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)

## Notes

---

### [mrmajumder](https://launchpad.net/~mrmajumder)

no upstream fix available as of 2026-08-28

## Severity score breakdown

CVSS version:

CVSS v4.0

[CVSS v4.0](https://ubuntu.com/security/CVE-2026-16554?format=md)
[CVSS v3.0](https://ubuntu.com/security/CVE-2026-16554?format=md)

**Base score**

5.1 · Medium

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Local |
  | Attack complexity | Low |
  | Attack requirements | None |
  | Privileges required | None |
  | User interaction | None |
  | Vulnerable system - Confidentiality impact | None |
  | Vulnerable system - Integrity impact | None |
  | Vulnerable system - Availability impact | Low |
  | Subsequent system - Confidentiality impact | Low |
  | Subsequent system - Integrity impact | Low |
  | Subsequent system - Availability impact | Low |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 5.1 · Medium |
  | Base + Threat score | - |
  | Base + Environmental score | - |
  | Base + Threat + Environmental score | - |

**Vector:** 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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-16554)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-16554)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2026-16554)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2026-16554)

### Other references

* <https://www.cve.org/CVERecord?id=CVE-2026-16554>
* <https://cert.pl/en/posts/2026/07/CVE-2026-16554>
* <https://github.com/DaveGamble/cJSON>