---
id: CVE-2024-53867
aliases:
  - GHSA-56w4-5538-8v8h
  - PYSEC-2026-1610
title: Synapse Matrix has a partial room state leak via Sliding Sync
summary: Synapse Matrix has a partial room state leak via Sliding Sync
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N'
vendor: matrix-synapse
product: matrix-synapse
ecosystem: pip
affected:
  - 'matrix-synapse >= 1.113.0rc1, < 1.120.1'
patched:
  - matrix-synapse 1.120.1
published: '2024-12-03'
updated: '2026-07-07'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-56w4-5538-8v8h'
references:
  - url: >-
      https://github.com/element-hq/synapse/security/advisories/GHSA-56w4-5538-8v8h
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2024-53867'
  - url: 'https://github.com/matrix-org/matrix-spec-proposals/pull/4186'
  - url: 'https://github.com/element-hq/synapse'
tags:
  - osv
  - pip
epss: 0.00442
epssPercentile: 0.3789
ingestedAt: '2026-07-08T18:25:45.796Z'
---

## Overview

### Impact
The Sliding Sync feature on Synapse versions between 1.113.0rc1 and 1.120.0 can leak partial room state changes to users no longer in a room. Non-state events, like messages, are unaffected.

### Patches
Synapse version 1.120.1 fixes the problem.

### Workarounds
Disable Sliding Sync.

### References
https://github.com/matrix-org/matrix-spec-proposals/pull/4186
https://github.com/element-hq/synapse/blob/d80cd57c54427687afcb48740d99219c88a0fff1/synapse/config/experimental.py#L341-L344

### For more information

If you have any questions or comments about this advisory, please email us at [security at element.io](mailto:security@element.io).


## Affected packages

- `matrix-synapse >= 1.113.0rc1, < 1.120.1`

## Remediation

Upgrade to a patched release:

- `matrix-synapse 1.120.1`