CVE-2023-32323

Name: CVE-2023-32323
Creator: NVD / NIST
Published: 2023-05-26T14:15:10.827+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4.3/10EPSS 0.98%

Last modified Jun 17, 2026

CVE-2023-32323 is a medium-severity vulnerability rated 4.3/10 on the CVSS scale. 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. EPSS estimates a 0.98% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

4.3/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

EPSS Probability

0.98%

57.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Matrix	Synapse	< 1.74.0

References

https://github.com/matrix-org/synapse/issues/14492Exploit, Issue Tracking
https://github.com/matrix-org/synapse/pull/14642Patch
https://github.com/matrix-org/synapse/security/advisories/GHSA-f3wc-3vxv-xmvrMitigation, Vendor Advisory
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UJIJRP5ZH6B3KGFLHCAKR2IX2Y4Z25QD/
https://github.com/matrix-org/synapse/issues/14492Exploit, Issue Tracking
https://github.com/matrix-org/synapse/pull/14642Patch
https://github.com/matrix-org/synapse/security/advisories/GHSA-f3wc-3vxv-xmvrMitigation, Vendor Advisory
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UJIJRP5ZH6B3KGFLHCAKR2IX2Y4Z25QD/

Timeline

Published: May 26, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-32323?

How severe is CVE-2023-32323?

CVE-2023-32323 has a CVSS score of 4.3/10 (MEDIUM severity). The EPSS model estimates a 0.98% probability of exploitation in the next 30 days.

How do I fix CVE-2023-32323?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2023-32323?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST