PyPI/matrix-synapse CVE-2021-21274: medium 4.3, EPSS 2.16%

Denial of service attack via .well-known lookups

Action: Upgrade matrix-synapse to 1.25.0 or later.

pip install matrix-synapse==1.25.0

Affected

Fixed versions

Sources

• osv: GHSA-2hwx-mjrm-v3g8
• https://github.com/matrix-org/synapse/security/advisories/GHSA-2hwx-mjrm-v3g8
• https://nvd.nist.gov/vuln/detail/CVE-2021-21274
• https://github.com/matrix-org/synapse/pull/8950
• https://github.com/matrix-org/synapse/commit/ff5c4da1289cb5e097902b3e55b771be342c29d6
• 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-2021-132.yaml
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY

CVE-2021-21274 · published 2021-03-01T19:34:54Z · modified 2026-09-10T03:49:14.211839612Z · JSON