{"action":"Upgrade matrix-synapse to 1.23.1 or later.","affected":[{"fixed":"1.23.1","introduced":"0"}],"component":"matrix-synapse","cve_ids":["CVE-2020-26257"],"ecosystem":"PyPI","epss":0.02392,"exploited":false,"fixed_versions":["1.23.1"],"ghsa_id":"GHSA-hxmp-pqch-c8mm","id":"tcs_01M5KFMQMBHEKKX6V624HD9YKA","modified_at":"2026-09-10T03:49:00.422107261Z","published_at":"2020-12-09T18:21:29Z","references":["https://osv.dev/vulnerability/GHSA-hxmp-pqch-c8mm","https://github.com/matrix-org/synapse/security/advisories/GHSA-hxmp-pqch-c8mm","https://nvd.nist.gov/vuln/detail/CVE-2020-26257","https://github.com/matrix-org/synapse/pull/8776","https://github.com/matrix-org/synapse/commit/3ce2f303f15f6ac3dc352298972dc6e04d9b7a8b","https://github.com/matrix-org/synapse/blob/develop/CHANGES.md#synapse-1231-2020-12-09","https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2020-236.yaml","https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/DBTIU3ZNBFWZ56V4X7JIAD33V5H2GOMC","https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QR4MMYZKX5N5GYGH4H5LBUUC5TLAFHI7"],"severity":{"label":"medium","score":6.5},"sources":[{"source":"osv","source_id":"GHSA-hxmp-pqch-c8mm","url":"https://osv.dev/vulnerability/GHSA-hxmp-pqch-c8mm"}],"summary":"Denial of service attack via incorrect parameters in Matrix Synapse"}