# CVE-2023-43796: matrix-synapse: Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remo...

CVE-2023-43796 is fixed in matrix-synapse on 1 platform, first by matrix-synapse 0.24.0+dfsg-1ubuntu0.1~esm4, released October 31, 2023. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2023-43796
- Priority: Routine
- CVSS: 5.3 (medium)
- EPSS: 0.0120
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 31, 2023

## Description

Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver. System administrators are encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | matrix-synapse Debian 14 | 1.95.1-1 | [DEBIAN-CVE-2023-43796](https://patchblox.com/security/data/fix/linux/debian-cve-2023-43796.md) | Oct 31, 2023 |
| Linux | matrix-synapse Ubuntu 18.04.6 LTS (bionic) | 0.24.0+dfsg-1ubuntu0.1~esm4 | [matrix-synapse 0.24.0+dfsg-1ubuntu0.1~esm4](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-matrix-synapse-0.24.0-dfsg-1ubuntu0.1-esm4.md) | Oct 31, 2023 |
| Linux | matrix-synapse Ubuntu 20.04 LTS (focal) | 1.11.0-1ubuntu0.1~esm2 | [matrix-synapse 1.11.0-1ubuntu0.1~esm2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-matrix-synapse-1.11.0-1ubuntu0.1-esm2.md) | Oct 31, 2023 |
| Linux | matrix-synapse Ubuntu 22.04.1 LTS (jammy) | 1.53.0-1ubuntu0.1~esm2 | [matrix-synapse 1.53.0-1ubuntu0.1~esm2](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-matrix-synapse-1.53.0-1ubuntu0.1-esm2.md) | Dec 3, 2024 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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