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Partial room state leak via Sliding Sync

Moderate
sandhose published GHSA-56w4-5538-8v8h Dec 3, 2024

Package

pip matrix-synapse (pip)

Affected versions

>= 1.113.0rc1, < 1.120.1

Patched versions

1.120.1

Description

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

matrix-org/matrix-spec-proposals#4186

synapse/synapse/config/experimental.py

Lines 341 to 344 in d80cd57

# MSC3575 (Sliding Sync) alternate endpoints, c.f. MSC4186.
#
# This is enabled by default as a replacement for the sliding sync proxy.
self.msc3575_enabled: bool = experimental.get("msc3575_enabled", True)

For more information

If you have any questions or comments about this advisory, please email us at security at element.io.

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

CVE ID

CVE-2024-53867

Weaknesses