---
title: "CVE-2026-54522\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-2026-54522?format=md
keywords: index, follow
---

# CVE-2026-54522

Publication date 30 July 2026

Last updated 7 August 2026

---

Ubuntu priority

**Medium**

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

## Cvss 3 Severity Score

**5.4 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2026-54522?format=md#impact-score)

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## Description

MessagePack for Ruby is an implementation of the MessagePack binary
serialization format. Prior to 1.8.2, MessagePack::Buffer#clear in
ext/msgpack/buffer.c leaves rmem\_last, rmem\_end, and rmem\_owner stale after
\_msgpack\_buffer\_shift\_chunk returns an rmem page to the shared pool,
allowing a subsequent Buffer#write and a second MessagePack::Buffer to
alias the page and disclose or corrupt cross-buffer data. This issue is
fixed in version 1.8.2.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| ruby-msgpack | 26.04 LTS resolute | Needs evaluation |
| 24.04 LTS noble | Needs evaluation |
| 22.04 LTS jammy | Needs evaluation |
| 20.04 LTS focal | Needs evaluation |
| 18.04 LTS bionic | Needs evaluation |
| 16.04 LTS xenial | Needs evaluation |

---

* [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-2026-54522?format=md)
[CVSS v3.0](https://ubuntu.com/security/CVE-2026-54522?format=md)

**Base score**

2.1 · Low

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 2.1 · Low |
  | Base + Threat score | - |
  | Base + Environmental score | - |
  | Base + Threat + Environmental score | - |

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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-54522)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-54522)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2026-54522)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2026-54522)

### Other references

* <https://www.cve.org/CVERecord?id=CVE-2026-54522>
* <https://github.com/msgpack/msgpack-ruby/security/advisories/GHSA-4mrv-5p47-p938>