# CVE-2024-31208: matrix-synapse: Synapse is an open-source Matrix homeserver

CVE-2024-31208 is fixed in matrix-synapse on 1 platform, first by DEBIAN-CVE-2024-31208, released April 23, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2024-31208
- Priority: Routine
- CVSS: 6.5 (medium)
- EPSS: 0.0146
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Apr 23, 2024

## Description

Synapse is an open-source Matrix homeserver. A remote Matrix user with malicious intent, sharing a room with Synapse instances before 1.105.1, can dispatch specially crafted events to exploit a weakness in the V2 state resolution algorithm. This can induce high CPU consumption and accumulate excessive data in the database of such instances, resulting in a denial of service. Servers in private federations, or those that do not federate, are not affected. Server administrators should upgrade to 1.105.1 or later. Some workarounds are available. One can ban the malicious users or ACL block servers from the rooms and/or leave the room and purge the room using the admin API.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | matrix-synapse Debian 14 | 1.103.0-2 | [DEBIAN-CVE-2024-31208](https://patchblox.com/security/data/fix/linux/debian-cve-2024-31208.md) | Apr 23, 2024 |
| 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 2026-11-08T19:12:23Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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