{"cve":"CVE-2025-30355","nvd":{"published":"2025-03-27T01:15:12.500","modified":"2026-06-17T09:08:34.360","status":"Analyzed","description":"Synapse is an open source Matrix homeserver implementation. A malicious server can craft events which, when received, prevent Synapse version up to 1.127.0 from federating with other servers. The vulnerability has been exploited in the wild and has been fixed in Synapse v1.127.1. No known workarounds are available.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-20"],"references":["https://github.com/element-hq/synapse/commit/2277df2a1eb685f85040ef98fa21d41aa4cdd389","https://github.com/element-hq/synapse/releases/tag/v1.127.1","https://github.com/element-hq/synapse/security/advisories/GHSA-v56r-hwv5-mxg6"],"products":["matrix:synapse"],"source":"nvd","synced_at":"2026-10-19T22:00:28.034033815+00:00"},"epss":{"cve":"CVE-2025-30355","score":0.01226,"percentile":0.68838,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-v56r-hwv5-mxg6","url":"https://osv.dev/vulnerability/GHSA-v56r-hwv5-mxg6","summary":"Synapse vulnerable to federation denial of service via malformed events","modified":"2026-07-07T17:56:23.043001848Z","packages":[{"ecosystem":"PyPI","name":"matrix-synapse","purl":"pkg:pypi/matrix-synapse","ranges":["<1.127.1"],"fixed":["1.127.1"]}]},{"id":"PYSEC-2026-1614","url":"https://osv.dev/vulnerability/PYSEC-2026-1614","summary":"Synapse vulnerable to federation denial of service via malformed events","modified":"2026-07-07T17:46:57.350680763Z","packages":[{"ecosystem":"PyPI","name":"matrix-synapse","purl":"pkg:pypi/matrix-synapse","ranges":["<1.127.1"],"fixed":["1.127.1"]}]}],"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."]}