{"action":"Upgrade matrix-synapse to 1.20.0 or later.","affected":[{"fixed":"1.20.0","introduced":"0"}],"component":"matrix-synapse","cve_ids":["CVE-2020-26890"],"ecosystem":"PyPI","epss":0.03004,"exploited":false,"fixed_versions":["1.20.0"],"ghsa_id":"GHSA-4mp3-385r-v63f","id":"tcs_01M5KEYJNF3FYJY345CMGKTTGP","modified_at":"2026-07-08T06:29:37.300767735Z","published_at":"2020-11-24T22:58:58Z","references":["https://osv.dev/vulnerability/GHSA-4mp3-385r-v63f","https://github.com/matrix-org/synapse/security/advisories/GHSA-4mp3-385r-v63f","https://nvd.nist.gov/vuln/detail/CVE-2020-26890","https://github.com/matrix-org/synapse","https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2020-237.yaml","https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/G7YXMMYQP46PYL664JQUXCA3LPBJU7DQ","https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/U34DPP4ZLOEDUY2ZCWOHQPU5GA5LYNUQ","https://pypi.org/project/matrix-synapse"],"severity":{"label":"high","score":7.5},"sources":[{"source":"osv","source_id":"GHSA-4mp3-385r-v63f","url":"https://osv.dev/vulnerability/GHSA-4mp3-385r-v63f"}],"summary":"Denial of service attack due to invalid JSON"}