---
title: "CVE-2026-101003\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-2026-101003?format=md
keywords: index, follow
---

# CVE-2026-101003

Publication date 29 September 2026

Last updated 30 September 2026

---

Ubuntu priority

**Medium**

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

## Cvss 3 Severity Score

**5.3 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2026-101003?format=md#impact-score)

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## Description

A weakness has been identified in Cesanta Mongoose up to 7.21. Affected by
this vulnerability is the function fn of the file
tutorials/mqtt/mqtt-server/main.c of the component MQTT Broker. Executing a
manipulation can lead to stack-based buffer overflow. The attack can be
launched remotely. The exploit has been made available to the public and
could be used for attacks. Upgrading to version 7.22 addresses this issue.
This patch is called a9df523f76f43a38bd53b4232b9cfd4c16869e71. Upgrading
the affected component is advised.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| mongoose | 26.04 LTS resolute | Not in release |
| 24.04 LTS noble | Not in release |
| 22.04 LTS jammy | Not in release |

---

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

## Severity score breakdown

CVSS version:

CVSS v4.0

[CVSS v4.0](https://ubuntu.com/security/CVE-2026-101003?format=md)
[CVSS v3.0](https://ubuntu.com/security/CVE-2026-101003?format=md)

**Base score**

5.5 · Medium

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Network |
  | 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 | None |
  | Subsequent system - Integrity impact | None |
  | Subsequent system - Availability impact | None |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 5.5 · Medium |
  | Base + Threat score | - |
  | Base + Environmental score | - |
  | Base + Threat + Environmental score | - |

**Vector:** CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-101003)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-101003)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2026-101003)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2026-101003)

### Other references

* <https://www.cve.org/CVERecord?id=CVE-2026-101003>
* <https://github.com/cesanta/mongoose/>
* <https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71>
* <https://github.com/cesanta/mongoose/releases/tag/7.22>
* <https://vuldb.com/cve/CVE-2026-101003>
* <https://vuldb.com/submit/920005>
* <https://vuldb.com/vuln/410873>
* <https://vuldb.com/vuln/410873/cti>