---
title: "CVE-2023-45129\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-2023-45129?format=md
keywords: index, follow
---

# CVE-2023-45129

Publication date 10 October 2023

Last updated 26 August 2025

---

Ubuntu priority

**Medium**

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

## Cvss 3 Severity Score

**4.9 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2023-45129?format=md#impact-score)

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## Description

Synapse is an open-source Matrix homeserver written and maintained by the
Matrix.org Foundation. Prior to version 1.94.0, a malicious server ACL
event can impact performance temporarily or permanently leading to a
persistent denial of service. Homeservers running on a closed federation
(which presumably do not need to use server ACLs) are not affected. Server
administrators are advised to upgrade to Synapse 1.94.0 or later. As a
workaround, rooms with malicious server ACL events can be purged and
blocked using the admin API.

[Read the notes from the security team](https://ubuntu.com/security/CVE-2023-45129?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| matrix-synapse | 24.10 oracular | Not affected |
| 24.04 LTS noble | Not affected |
| 23.10 mantic | Ignored end of life, was needs-triage |
| 23.04 lunar | Ignored end of life, was needs-triage |
| 22.04 LTS jammy | Ignored patch infeasible |
| 20.04 LTS focal | Ignored end of standard support, was ignored [patch infeasible] |
| 18.04 LTS bionic | Ignored end of standard support |
| 16.04 LTS xenial | Not in release |
| 14.04 LTS trusty | 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)

## Notes

---

### [john-breton](https://launchpad.net/~john-breton)

Both rust/src and stubs/synapses (which the patch targets)
DNE in bionic-jammy. Without that functionality, patching
is infeasible, and those modules require significant
revisions to even get to function with the older versions.

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

4.9 · Medium

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Network |
  | Attack complexity | Low |
  | Privileges required | High |
  | User interaction | None |
  | Scope | Unchanged |
  | Confidentiality impact | None |
  | Integrity impact | None |
  | Availability impact | High |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 4.9 · Medium |
  | Exploitability score | - |
  | Impact score | - |

**Vector:** CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-45129)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2023-45129)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2023-45129)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2023-45129)

### Other references

* <https://github.com/matrix-org/synapse/security/advisories/GHSA-5chr-wjw5-3gq4>
* <https://github.com/matrix-org/synapse/pull/16360>
* <https://matrix-org.github.io/synapse/latest/admin_api/rooms.html#version-2-new-version>
* <https://www.cve.org/CVERecord?id=CVE-2023-45129>