---
id: CVE-2023-43796
aliases:
  - GHSA-mp92-3jfm-3575
  - PYSEC-2023-230
title: Synapse vulnerable to leak of remote user device information
summary: Synapse vulnerable to leak of remote user device information
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'
vendor: matrix-synapse
product: matrix-synapse
ecosystem: pip
affected:
  - matrix-synapse < 1.95.1
patched:
  - matrix-synapse 1.95.1
published: '2023-10-31'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:49:24.728166201Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-mp92-3jfm-3575'
references:
  - url: >-
      https://github.com/matrix-org/synapse/security/advisories/GHSA-mp92-3jfm-3575
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2023-43796'
  - url: >-
      https://github.com/matrix-org/synapse/commit/daec55e1fe120c564240c5386e77941372bf458f
  - url: 'https://github.com/matrix-org/synapse'
  - url: >-
      https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2023-230.yaml
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2IDEEZMFJBDLTFHQUTZRJJNCOZGQ2ZVS
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/VH3RNC5ZPQZ4OKPSL4E6BBJSZOQLGDEY
  - url: 'https://security.gentoo.org/glsa/202401-12'
tags:
  - osv
  - pip
epss: 0.00897
epssPercentile: 0.57836
ingestedAt: '2026-09-12T03:13:01.711Z'
---

## Overview

### Impact
Cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver.

### Patches
System administrators are encouraged to upgrade to Synapse 1.95.1 as soon as possible.

### Workarounds
The `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.

## Affected packages

- `matrix-synapse < 1.95.1`

## Remediation

Upgrade to a patched release:

- `matrix-synapse 1.95.1`