Medium severity · published May 26, 2023
CVE-2023-32323
Synapse Outgoing federation to specific hosts can be disabled by sending malicious invites
4.3
CVSS
1%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)1.0% · higher than 62% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
SY
synapse · matrix-org
< 1.74.0 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2023-32323
CVE.org
https://www.cve.org/CVERecord?id=CVE-2023-32323
Exploit
https://github.com/matrix-org/synapse/issues/14492
Patch
https://github.com/matrix-org/synapse/pull/14642
Mitigation
https://github.com/matrix-org/synapse/security/advisories/GHSA-f3wc-3vxv-xmvr
lists.fedoraproject.org
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UJIJRP5ZH6B3KGFLHCAKR2IX2Y4Z25QD/
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