Headline
GHSA-pfw4-xjgm-267c: Dendrite signature checks not applied to some retrieved missing events
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.
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
- GHSA-pfw4-xjgm-267c
- https://nvd.nist.gov/vuln/detail/CVE-2022-39200
- matrix-org/dendrite@2792d04
Related news
Dendrite is a Matrix homeserver written in Go. In affected versions events retrieved from a remote homeserver using the `/get_missing_events` path 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. The problem has been fixed in Dendrite 0.9.8. Users are advised to upgrade. There are no known workarounds for this issue.