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Denial of service due to incorrect application of event authorization rules

High severity GitHub Reviewed Published Aug 31, 2022 in matrix-org/synapse • Updated Jan 30, 2023

Package

pip matrix-synapse (pip)

Affected versions

< 1.62

Patched versions

1.62

Description

Impact

The Matrix specification specifies a list of event authorization rules which must be checked when determining if an event should be accepted into a room.

In versions of Synapse up to and including v1.61, some of these rules are not correctly applied. An attacker could craft events which would be accepted by Synapse but not a spec-conformant server, potentially causing divergence in the room state between servers.

Patches

Administrators of homeservers with federation enabled are advised to upgrade to v1.62.0 or higher.

Workarounds

References

For more information

If you have any questions or comments about this advisory, e-mail us at security@matrix.org.

References

@richvdh richvdh published to matrix-org/synapse Aug 31, 2022
Published to the GitHub Advisory Database Aug 31, 2022
Reviewed Aug 31, 2022
Published by the National Vulnerability Database Sep 2, 2022
Last updated Jan 30, 2023

Severity

High

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
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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:N/UI:N/S:U/C:N/I:N/A:H

EPSS score

0.129%
(48th percentile)

Weaknesses

CVE ID

CVE-2022-31152

GHSA ID

GHSA-jhjh-776m-4765

Source code

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