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Dendrite signature checks not applied to some retrieved missing events

High severity GitHub Reviewed Published Sep 12, 2022 in matrix-org/dendrite • Updated Feb 2, 2023

Package

gomod github.com/matrix-org/dendrite (Go)

Affected versions

< 0.9.8

Patched versions

0.9.8

Description

Impact

Events retrieved from a remote homeserver using /get_missing_events did not have their signatures verified correctly. This could potentially allow a remote homeserver to provide invalid/modified events to Dendrite via this endpoint.

Note that this does not apply to events retrieved through other endpoints (e.g. /event, /state) as they have been correctly verified.

Homeservers that have federation disabled are not vulnerable.

Patches

The problem has been fixed in Dendrite 0.9.8.

Workarounds

There are no workarounds.

Special thanks

Tulir Asokan, who spotted the issue originally.

References

@neilalexander neilalexander published to matrix-org/dendrite Sep 12, 2022
Published by the National Vulnerability Database Sep 12, 2022
Published to the GitHub Advisory Database Sep 15, 2022
Reviewed Sep 15, 2022
Last updated Feb 2, 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
Low
Integrity
Low
Availability
Low

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:L/I:L/A:L

EPSS score

0.061%
(28th percentile)

Weaknesses

CVE ID

CVE-2022-39200

GHSA ID

GHSA-pfw4-xjgm-267c

Source code

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