CVE-2023-32323
Synapse Outgoing federation to specific hosts can be disabled by sending malicious invites
Description
Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. A malicious user on a Synapse homeserver X with permission to create certain state events can disable outbound federation from X to an arbitrary homeserver Y. Synapse instances with federation disabled are not affected. In versions of Synapse up to and including 1.73, Synapse did not limit the size of `invite_room_state`, meaning that it was possible to create an arbitrarily large invite event. Synapse 1.74 refuses to create oversized `invite_room_state` fields. Server operators should upgrade to Synapse 1.74 or newer urgently.
How to fix CVE-2023-32323
To remediate CVE-2023-32323, upgrade the affected package to a fixed version below.
- —upgrade to 1.74.0-1 or later
- —upgrade to 1.74.0 or later
- —upgrade to 1.74.0 or later
Is CVE-2023-32323 being exploited?
Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.
Affected packages (3)
- from 0, < 1.74.0-1
- from 0, < 1.74.0
- from 0, < 1.74.0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:L |
| osv | CVSS 3.1 | MEDIUM5.0 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:L |