{"action":"Upgrade matrix-synapse to 1.25.0 or later.","affected":[{"fixed":"1.25.0","introduced":"0"}],"component":"matrix-synapse","cve_ids":["CVE-2021-21273"],"ecosystem":"PyPI","epss":0.018,"exploited":false,"fixed_versions":["1.25.0"],"ghsa_id":"GHSA-v936-j8gp-9q3p","id":"tcs_01M5KFZQ0VQDR5071AA9Y3ZSXE","modified_at":"2026-07-08T06:27:53.790549567Z","published_at":"2021-02-26T17:28:34Z","references":["https://osv.dev/vulnerability/GHSA-v936-j8gp-9q3p","https://github.com/matrix-org/synapse/security/advisories/GHSA-v936-j8gp-9q3p","https://nvd.nist.gov/vuln/detail/CVE-2021-21273","https://github.com/matrix-org/synapse/pull/8821","https://github.com/matrix-org/synapse/commit/30fba6210834a4ecd91badf0c8f3eb278b72e746","https://github.com/matrix-org/synapse","https://github.com/matrix-org/synapse/releases/tag/v1.25.0","https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2021-131.yaml","https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY"],"severity":{"label":"low","score":3.1},"sources":[{"source":"osv","source_id":"GHSA-v936-j8gp-9q3p","url":"https://osv.dev/vulnerability/GHSA-v936-j8gp-9q3p"}],"summary":"Open redirects on some federation and push requests"}