id: PYSEC-2026-1610
published: "2026-07-07T14:34:46.676923Z"
modified: "2026-07-07T17:24:38.563328Z"
aliases:
- CVE-2024-53867
- GHSA-56w4-5538-8v8h
summary: Synapse Matrix has a partial room state leak via Sliding Sync
details: "### Impact\nThe 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.\n\n### Patches\nSynapse version 1.120.1 fixes the problem.\n\n### Workarounds\nDisable Sliding Sync.\n\n### References\nhttps://github.com/matrix-org/matrix-spec-proposals/pull/4186\nhttps://github.com/element-hq/synapse/blob/d80cd57c54427687afcb48740d99219c88a0fff1/synapse/config/experimental.py#L341-L344\n\n### For more information\n\nIf you have any questions or comments about this advisory, please email us at [security at element.io](mailto:security@element.io).\n"
affected:
- package:
    name: matrix-synapse
    ecosystem: PyPI
    purl: pkg:pypi/matrix-synapse
  ranges:
  - type: ECOSYSTEM
    events:
    - introduced: 1.113.0rc1
    - fixed: 1.120.1
  versions:
  - 1.113.0
  - 1.113.0rc1
  - 1.114.0
  - 1.114.0rc1
  - 1.114.0rc3
  - 1.115.0
  - 1.115.0rc1
  - 1.115.0rc2
  - 1.116.0
  - 1.116.0rc1
  - 1.116.0rc2
  - 1.117.0
  - 1.117.0rc1
  - 1.118.0
  - 1.118.0rc1
  - 1.119.0
  - 1.119.0rc2
  - 1.120.0
  - 1.120.0rc1
references:
- type: WEB
  url: https://github.com/element-hq/synapse/security/advisories/GHSA-56w4-5538-8v8h
- type: ADVISORY
  url: https://nvd.nist.gov/vuln/detail/CVE-2024-53867
- type: WEB
  url: https://github.com/matrix-org/matrix-spec-proposals/pull/4186
- type: PACKAGE
  url: https://github.com/element-hq/synapse
- type: PACKAGE
  url: https://pypi.org/project/matrix-synapse
- type: ADVISORY
  url: https://github.com/advisories/GHSA-56w4-5538-8v8h
severity:
- type: CVSS_V3
  score: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N