{"cve":"CVE-2023-32323","nvd":{"published":"2023-05-26T14:15:10.827","modified":"2026-06-17T05:58:34.297","status":"Modified","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_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L","score":4.3},"cwes":["CWE-20"],"references":["https://github.com/matrix-org/synapse/issues/14492","https://github.com/matrix-org/synapse/pull/14642","https://github.com/matrix-org/synapse/security/advisories/GHSA-f3wc-3vxv-xmvr","https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UJIJRP5ZH6B3KGFLHCAKR2IX2Y4Z25QD/","https://github.com/matrix-org/synapse/issues/14492"],"products":["matrix:synapse"],"source":"nvd","synced_at":"2026-10-19T21:38:24.161619714+00:00"},"epss":{"cve":"CVE-2023-32323","score":0.00981,"percentile":0.62278,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-f3wc-3vxv-xmvr","url":"https://osv.dev/vulnerability/GHSA-f3wc-3vxv-xmvr","summary":"Synapse Outgoing federation to specific hosts can be disabled by sending malicious invites","modified":"2025-02-13T19:13:53.959033Z","packages":[{"ecosystem":"PyPI","name":"matrix-synapse","purl":"pkg:pypi/matrix-synapse","ranges":["<1.74.0"],"fixed":["1.74.0"]}]},{"id":"PYSEC-2023-67","url":"https://osv.dev/vulnerability/PYSEC-2023-67","summary":"","modified":"2023-11-08T04:12:34.841195Z","packages":[{"ecosystem":"PyPI","name":"matrix-synapse","purl":"pkg:pypi/matrix-synapse","ranges":["<1.74.0"],"fixed":["1.74.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}