MEDIUM 4.3

GHSA-56w4-5538-8v8h

Synapse Matrix has a partial room state leak via Sliding Sync

Details

### 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).

Are you affected?

Enter the version of the package you're using.

Affected packages

PyPI / matrix-synapse

Introduced in: 1.113.0rc1 Fixed in: 1.120.1

Fix pip install --upgrade 'matrix-synapse>=1.120.1'

References

https://github.com/element-hq/synapse/security/advisories/GHSA-56w4-5538-8v8h [WEB]
https://nvd.nist.gov/vuln/detail/CVE-2024-53867 [ADVISORY]
https://github.com/matrix-org/matrix-spec-proposals/pull/4186 [WEB]
https://github.com/element-hq/synapse [PACKAGE]