https://cve.radiocsirt.org/rss/recent/all/10 Most recent entries from all 2026-10-18T13:46:02.397930+00:00 Vulnerability-Lookup csirt@opendfir.org python-feedgen Contains only the most 10 recent entries. https://cve.radiocsirt.org/vuln/cnvd-2021-15493 cnvd-2021-15493 2026-10-18T13:46:02.402317+00:00 cnvd-2021-15493 https://cve.radiocsirt.org/vuln/euvd-2026-22085 EUVD-2026-22085 2026-10-18T13:46:02.402350+00:00 EUVD-2026-22085 https://cve.radiocsirt.org/vuln/fkie_cve-2021-21274 fkie_cve-2021-21274 2026-10-18T13:46:02.402381+00:00

Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.25.0, a malicious homeserver could redirect requests to their .well-known file to a large file. This can lead to a denial of service attack where homeservers will consume significantly more resources when requesting the .well-known file of a malicious homeserver. This affects any server which accepts federation requests from untrusted servers. Issue is resolved in version 1.25.0. As a workaround the `federation_domain_whitelist` setting can be used to restrict the homeservers communicated with over federation.

 https://cve.radiocsirt.org/vuln/ghsa-2hwx-mjrm-v3g8 GHSA-2hwx-mjrm-v3g8 — Denial of service attack via .well-known lookups 2026-10-18T13:46:02.402448+00:00

Affected: PyPI: matrix-synapse

### Impact A malicious homeserver could redirect requests to their .well-known file to a large file. This can lead to a denial of service attack where homeservers will consume significantly more resources when requesting the .well-known file of a malicious homeserver.

This affects any server which accepts federation requests from untrusted servers.

### Patches Issue is resolved by #8950. A bug not affecting the security aspects of this was fixed in #9108.

### Workarounds The `federation_domain_whitelist` setting can be used to restrict the homeservers communicated with over federation.

 https://cve.radiocsirt.org/vuln/gsd-2021-21274 gsd-2021-21274 2026-10-18T13:46:02.402491+00:00 gsd-2021-21274 https://cve.radiocsirt.org/vuln/pysec-2021-132 PYSEC-2021-132 2026-10-18T13:46:02.402516+00:00

Affected: PyPI: matrix-synapse

Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.25.0, a malicious homeserver could redirect requests to their .well-known file to a large file. This can lead to a denial of service attack where homeservers will consume significantly more resources when requesting the .well-known file of a malicious homeserver. This affects any server which accepts federation requests from untrusted servers. Issue is resolved in version 1.25.0. As a workaround the `federation_domain_whitelist` setting can be used to restrict the homeservers communicated with over federation.

 https://cve.radiocsirt.org/vuln/ubuntu-cve-2021-21274 UBUNTU-CVE-2021-21274 2026-10-18T13:46:02.402561+00:00

Affected: Ubuntu:Pro:18.04:LTS: matrix-synapse, Ubuntu:Pro:20.04:LTS: matrix-synapse

Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.25.0, a malicious homeserver could redirect requests to their .well-known file to a large file. This can lead to a denial of service attack where homeservers will consume significantly more resources when requesting the .well-known file of a malicious homeserver. This affects any server which accepts federation requests from untrusted servers. Issue is resolved in version 1.25.0. As a workaround the `federation_domain_whitelist` setting can be used to restrict the homeservers communicated with over federation.